Business model viability, in the majority of startups, will come down
to balancing two variables:
- Cost to Acquire Customers (CAC)
- The ability to monetize those customers, or LTV (which stands for
Lifetime Value of a Customer)

http://www.forentrepreneurs.com/startup-killer/

Via Babak Nivi on Quora:
http://www.quora.com/Babak-Nivi/Always-assume-competition

I just got this email from a friend:

"Why didn't you ever tell me about this site? This is exactly what
I was trying to create and just spent the last few weeks pulling
people together to build me a site. Do you know how they are doing?
They never once came up through my competitive intelligence and I just
learned about them. Would like to know before I dump anymore money in
my venture.”

My response:

“I can't give you any insider information on any of these
companies. I know the founders of all of them. It doesn't matter. It
has nothing to do with you. It's good to know the market but the
competition is irrelevant. The market is big. Winning comes by knowing
the customer better, executing better, and continuing to work on the
problem after sane people have cashed out. If a competitor is going to
scare you, you shouldn't have started a business in the first place.
Every big market or successful business will attract competitors
anyway. Always assume competition.”

What’s the one thing that your startup will do and do
better than everyone else?

http://betashop.com/post/4066229168/the-only-question-your-startup-needs-to-a...

Fact is, startups are all about making things people want,
not being a great developer. Your program is number 50 on the list of
important things for you to do. You might write 10 lines of Javascript
and make a million bucks. Or you might write the cleanest, most
gorgeous code anybody has ever seen and make zero.

http://www.whattofix.com/blog/archives/2011/02/programmer-as-m.php

About once a month, I get a call from someone that won't
tell me the idea, but still wants advice and even introductions.
Yikes! I just tell them to stop. They're not ready yet.

http://www.humbledmba.com/startups-in-stealth-mode-need-one-piece-of-ad

Look, your lack of progress pretty much stems from things
you’re avoiding because a) you are unsure of how they’re done, or b)
you’re unconsciously (or consciously!) unwilling to do them. In other
words, you are a fucking pussy.

If you know what a URL is and if you know how to use most
of the Apps on your iPhone you and part of a small group of experts.
Don’t assume you are the default because you are the exception. Make
your apps, websites and tools as simple as possible and always test
with other people.

http://thenextweb.com/entrepreneur/2010/10/25/compared-to-you-most-people-see...

When I asked Jared Spool (the founder of User Interface
Engineering) why so few UX researchers join early stage startups, he
replied: “"Startups are run by entrepreneurs. Entrepreneurs know
everything. They don’t listen. A UX researcher would be frustrated."”
That made me wonder… is there a class of startups where the
entrepreneurs are eager to listen?

http://www.uxbooth.com/blog/lean-startups-and-user-experience-design/

http://blog.getsatisfaction.com/2010/10/04/fastest-way-to-lose-customers/

http://www.chubbybrain.com/blog/2010/10/startup-failure-post-mortem/

All the hindsight you could want.