I've worked for several early stage startups in my career and not a single one has paid off. In fact, I've lost money (a few thousand $$) purchasing ISOs at each company. If you want to work at an early-stage start-up, do it because you want to learn fast, want a lot of responsibility, and you love the industry, not because of the chance of getting rich - because if that's the only reason you're doing it, you might as well buy lotto tickets. Value your ISOs at zero, make sure your cash comp is reasonable, and ask for the same amount of ISOs are the previous person hired at your level.