Heinlein's Rules for Writing (Mostly)

Back in 1947, in an essay titled "On the Writing of Speculative Fiction" (since reprinted several times), Robert Heinlein wrote five rules for people who want to become professional writers. They've been republished many times, and for the most part, they're still good (I'll get to that "most part" in a minute).

The rules are:

1. You must write.

2. You must finish what you start.

3. You must refrain from rewriting except to editorial order.

4. You must put it on the market

5. You must keep it on...