How much do you believe in the company? When you talk to the founders, do you get the feeling that they're likely to be successful? Do you like taking risks?

How much do you believe in the company? When you talk to the founders, do you get the feeling that they're likely to be successful? Do you like taking risks? Would you be mad if the startup flopped? Just ask yourself a bunch of questions about how much you'd enjoy the opportunity if you take a pay cut and the options turn out to be worthless. I think that is a better measure than trying to guesstimate the value of the options.