The short answer
Enough that money stress does not cloud your judgment, and no more. In the early days many founders underpay themselves to stretch runway, which is fine for a while but corrodes decision making if it drags on for years. A workable frame: cover your real fixed costs plus a modest buffer, revisit the number at every raise, and write your salary into the plan you show investors rather than treating it as an afterthought. Underpaying yourself is not a virtue, it is a risk you are quietly carrying.
A curated summary to orient you, not advice. The resources below are the real value.