I agree with this -- get as much cash as possible, not equity. If they are not successful, you come out ahead. If they are successful, you will probably be so diluted, that it won't matter to you. Get your expenses and 11 x (difference between your monthly salary and a market salary).

(I AM NOT AN ACCOUNTANT, but) If they give you equity, and the company has a set valuation (if they took funding), then the equity has an established value that you pay taxes on (cash out of pocket).