Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

What should I look at before investing in a start-up?
You seem to have all your financial bases covered, and others have given you good financial advice, so I will try to give you some non-financial ideas. The first and most important thing is that you are investing with a long time friend, so the dynamics are a lot different that if you had recently met a stranger with an "interesting" new idea. The first thing you need to ask yourself is if your friendship will survive if this thing doesn't go well? You've already said you can afford to lose the money so that's not a worry, but will there be any "recriminations?" The flip side is also true; if the venture succeeds, you should be able to go further with it because he's your friend. You know your friend better (back to grade school) than almost anyone else, so here are some things to ask yourself: What does your friend have that will give him a chance to succeed; tech savvy, a winning personality, a huge rolodex, general business savvy, something else? If your guardian angel had told you that one of your friends was planning to embark on an internet/advertising venture, is this the one you would have guessed? Conversely, knowing that your friend was planning to do a start up, is this the kind of venture you would have guessed? How does "internet" and "advertising" fit in with what you are doing? If this venture succeeds, could it be used to help your professional development and career, maybe as a supplier or customer? Can you see yourself leaving your current job and joining your friend's (now established) company as a vice president or acting as a member of its board of directors, the latter perhaps while pursuing your current career path?  Are your other mutual friends investing? Are some of them more tech savvy than you and better able to judge the company's prospects of success? To a certain extent, there is "safety in numbers" and even if there isn't, "misery loves company." On the upside, would you feel left out if everyone in your crowd caught "the next Microsoft" except you?