While I cant speak from a perspective of personal experience regarding participation in ycombinator; I am currently prepping myself and my idea for this upcoming summer event; and I do think I have a bit of useful advice to offer other founders who are (much like myself) aspiring to not only get their startup idea accepted into ycombinator; but ultimately end up with an outcome where they receive the funding necessary to kickstart their business. So I am just going to list of a few principles I believe are most important to maximize the chances of success in ycombinator that you should get down before a founder should even consider applying.
1. Do your homework.
(I) There are a ton of books and blog posts that I highly recommend founders read before they consider applying. Here is a list of the books I am currently reading and why I think they are so important.
(A) The Steve Jobs biography.
First off, This book is a fantastic read; plain and simple. I'd recommend it to someone who didn't understand a thing about tech just because how fascinating the story of Steve Job's life was.
Now as my recommendation pertains to aspiring entrepreneurs, Even if you aren't a fan of Apple's products and/or Steve Jobs (i.e his philosophies, his personality, w/e); only a fool would say Job's wasn't one of the greatest founders to ever live. His story is a keen example that demonstrates the best AND worst qualities of a founder. My short summary of the most important message you will get out of this book is thus:
Success is produced by strong, passionate leadership that can maintain a well balanced sense of self-conviction when it comes to mandating the set of core values they believe will pave the way that brings their vision into fruition.
For Steve Jobs, his up and down battle with his self-conviction made him a great leader because he refused to compromise on his vision on what Apple should stand for; but at times it made him a bad leader because he was inclined to alienate people and ideas that didn't integrate into his volatile, constantly evolving black and white views of the world.
There is a fine line between a rational reality and an irrational one; and when people refer to his "reality distortion field" effect, I think it is misleading to label of it that way because it seems to paint him as a snake-oil salesmen. Rather I think he just had a cunning way to point out when our perception of what's possible is being biased by our flawed perception of how we interpret the divisionary line that our sense of rationality projects.
(B) Business Adventures
Bill Gates turned me onto this book in one of his Gate Notes post. Its a bit dated (the copyrights are dated from 1959-1969) so its stories aren't 100% relevant to today's world (e.g there is a story about the stock market freaking out because stock updates back then could get overloaded and jammed because updates to a stock was communicated by a computer printing output via paper tape); however with that being said, the core morals and points addressed in the book regarding good vs bad business (e.g. marketing, product design, brand awareness, technological limitations, etc) is pretty enlightening, entertaining, and perhaps even motivational because there are stories that show that even the most successful companies and business savvy entrepreneurs experience epic fails from time to time.
(C) All the books and articles Y-Combinator recommends at http://ycombinator.com/resources
I have only started diving into these books and articles, so I can't say much about my experience reading them, however I have read a bunch of Paul Grahams blog posts; and I can say they are quite entertaining. (Though I dont always agree with his opinion, I do find his perspective on things interesting to ponder about.)
However, even though I haven't read them yet; I still recommend them because the key purpose of Y Combinator (imho) isnt to help get your startup buzz and financed; rather the key purpose is to teach founders how to turn their grand vision into a successful company. Everything else that happens at Y-Combinator, (investor meetups, articles of incorporation, press exposure etc) is just them helping nudge startups out to sea. If the startup's crew doesn't know how to properly set the sails on boat before they undock the startup wont get anywhere anytime soon. (which leaves the startup vulnerable to mutiny, sinkage, spoiled and/or depleted resources, etc)
If you are a founder applying for ycombinator, and you (and your other founders) haven't read all of the recommended reading yet (or even worse don't plan on it), you aren't doing one of the most important things you need to do as a founder to succeed; putting in the work that mitigates risk of failure.
(D) cat-v considered harmful
This is a paper written by Rob Pike that made me a better engineer by several orders of magnitude.
It really opened my eyes to the inherent beauty and elegance to the concept of simplicity. If you haven't yet come to this revelation I implore you to read the article and ponder on this quote.
"Simplicity is the ultimate sophistication" (quote origins disputed but many attribute it to Da Vinci)
If you look at many of the most successful products out in the market one trend that should be the most apparent is that the most elegantly simple and fresh products with the best marketing tend to win. That's why fast food is so successful. That is why iPhone was a smash hit. That is why Google Search is a billion dollar company. That is why facebook beat myspace. That is why Starbucks is successful even though they charge 2000x markup on what it would cost to brew your own coffee at home when you wake up. If simplicity isn't something you incorporate into every aspect of your business, a competitor will pop up that does, and they will gobble you up like Pacman on power pills.
http://harmful.cat-v.org/cat-v/
(II) Videos worth watching.
(A) How To Start a Startup
The reasoning for this recommendation is the same as the reasoning I stated above regarding the ycombinator recommended reading. (since this is the ycombinator sponsored standford class)
https://www.youtube.com/channel/UCxIJaCMEptJjxmmQgGFsnCg
http://techcrunch.com/2014/09/16/y-combinator-will-teach-a-class-on-startups-at-stanford-this-fall/
(B) Alexis Ohanian - Making Something People Love.
Considering that Alexis is a Y Combinator "O-G", I probably don't even need to try to explain why I recommend this for founders; but I'll go ahead and give my two cents out of respect.
If I had to narrow down the number 1 trait thats makes Alexis an extremely great founder in my mind, I'd have to say it's his overwhelming sense of compassion for people and that compassion is reflected into the products he helps build. If I were to take a guess at the reasons Paul Graham asked Steve and Alexis to come back to discuss a new idea after rejecting their "MMM" (my mobile menu i believe?) app, I would assume that Alexis' and Steve's compassion and ambition to build something users love, played a big part in that decision.
One of the most important lessons I took away from this video (and other talks given by alexis) was that if I didn't feel personally compassionate enough about my startup idea, it is probably not the right idea for me to submit to Y Combinator and attempt to pursue.
https://www.youtube.com/watch?v=KKYkmYuk5l8
(C) Public Static Void
Here is another rob pike related recommendation that discusses over complexity in technology.
https://www.youtube.com/watch?v=5kj5ApnhPAE
2. Know which technologies to invest in.
(I) Recruitment
One of the biggest challenges in building a successful startup is finding the best engineers, and in my opinion the best engineers tend to flock to the state of the art tools that make their lives easiest. Current trending technologies that come to mind that are worth investigating (imho) are tools like...
(A) CoreOS
CoreOS is a great OS because it is built around the premise that your web service will grow in traffic and at some point your service will have to scale and run seamlessly on more than one system. (hardware or vm)
In my views, I think it is best to build web based apps from the ground up under the premise that one day your app will handle millions of page views a day. Its easier to build for scale at the beginning, rather than realizing 2 years down the road that whatever technology you are using now just can't scale to satisfy your app's heavy traffic load anymore.
https://coreos.com/
(B) Go or Rust
This recommendation will probably spark a holy war debate, but regardless of how you feel about the languages, the fact is that when it comes to finding the BEST engineers; they tend to WANT a job where they can use one of these language. Of course, they are in short supply so you might be more fortunate finding a Ruby, Python, or Scala developer.
But there are technical flaws to consider in all languages, and it is important to consider a language that will satisfy your needs now and later down the road.
http://blog.iron.io/2013/03/how-we-went-from-30-servers-to-2-go.html
3. Research the market you are trying to enter/create.
(A) Think about how to generate revenue from day 1.
I am personally not a big fan of the whole, "focus on getting users now and worry about generating revenue later" philosophy that seems to be a popular trend in startups nowadays. I personally believe that there are huge opportunities to innovate how revenue is generated in web based applications, and I believe opting out of thinking about how your app will generate revenue until later, is basically a cop out decision to one day just do what every other web based company does nowadays after they gain a significant userbase. (Force ads on them; sell their info to the highest bidder; provide only half of the site to users for free; etc, etc...)
Unfortunately, some web applications are harder to monetize than others; so perhaps advertisements and data mining are the only options for a startup. However, that doesn't mean founders shouldn't consider take into consideration the potential for innovation when it comes to how their product generates revenue.
(B) Your idea doesn't need to be 100% original. It just needs to be 100x better than the competition.
John Graham-Cumming, "Turing's Curse"
https://www.youtube.com/watch?v=hVZxkFAIziA
If you watch this video, it becomes immediately clear that the term "innovation" in tech is nothing more than something we say when we upgrade our wagons from wooden spoke wheels to tires with 20 inch spinner rims.
Your idea doesn't need to create a new market to win big, it just needs to be better than whatever currently exists.
Apple didn't create the personal computer market, they just made a product that was 100xs better than it's competitor's products.
http://en.wikipedia.org/wiki/Microcomputer#History
Google didn't create the search engine market. they just made a product that was 100xs better than it's competitor's products.
http://en.wikipedia.org/wiki/Web_search_engine#History
The list goes on and on and on and on and on.
I think everybody here has heard the Picasso quote that Steve Jobs' has stated on numerous occasions.
"Good artists copy, Great artists steal"
Many people believe Steve Jobs is a hypocrite for using this quote and later trying to sue Microsoft and Google for patent infringement; and in my opinion they just don't understand what Picasso meant by using the term "steal".
The best example I know of that makes Picasso's quote crystal clear is quote Trent Reznor gave regarding his impression of Johnny Cash's cover of his song "Hurt".
http://en.wikipedia.org/wiki/Hurt_%28Nine_Inch_Nails_song%29#Background
4. just a quick aside regarding another Steve Jobs quote that I find rather interesting to ponder about.
When steve presented the Macintosh he described it as "Insanely Great"; which is a bit ironic because one of the very few pieces of furniture he kept in his house at that time was a portrait of Albert Einstine, who once said,
"Insanity: doing the same thing over and over again and expecting different results."
The reason I find this ironic stems from the fact that Steve Jobs obtained the inspiration for the Macintosh's GUI from a deal made with Xerox where they agreed to show him and his team a demonstration of the technology they developed for their Alto Computer in exchange for a stake in Apple. However after Xerox demoed the Alto to Apple, they tried to commercialize the technology and beat Apple to market with a workstation they developed soon afterwards called the Xerox Star; which was a total commercial flop. I wonder if Steve deliberately called the Macintosh "insanely great" as a way of paying homage to Einstein while taking a jab at the Xerox Star?