Ultimately, even if you follow the advice of a mentor or board member, it's still your fault if they were wrong!

The best mentors present their opinions simply as data and not as direction.

There's no law that says you have to do what your mentor suggests. And the sooner you learn how to say 'no' confidently, the easier it will be to manage these key relationships.

Because one of the main jobs of a CEO is to set the vision and strategy for the company, I'm a big believer in making one of the founders the default CEO.

Deciding whether or not to bring in an outside CEO is one of the most gut-wrenching decisions that a founder will ever need to make.

The Internet is full of choices, and nobody is going to make the choice to use a product that is hard to use or unattractive.

Consumers have zero time for products that are not simple, intuitive, and attractive to use. This is especially true with Internet products, where clean and useful design is a prerequisite to keeping anyone on your site for more than 30 seconds.

If you're pitching to investors for the first time and expecting them to be so blown away by how thoroughly amazing your pitch is that they write a check on the spot - well, prepare to be disappointed.

Twitter needs to become more of a platform on the web. If Twitter went away today, people would just turn to Facebook. If Facebook went away, people would start screaming - it's so universal.

San Francisco is a great startup community that you shouldn't even try to model yourself after because it's just special.