Start high. Don’t give current compensation. Don’t accept if you feel underpaid. It’s not really much different than negotiation with a big corp, other than the equity, which is a huge topic in itself for startups.

Just remember you deserve to be paid something equivalent to the value you will add to the business.

First one to mention a number (money), loses.

In a similar vein, have other options available. That gives you ultimate negotiating power.