Psi and/or magical powers, if real, are nearly useless.
Never be embarrassed or ashamed by anything you choose to write.
I'd visit the near future, close enough that someone might want to talk to Larry Niven and can figure out the language; distant enough to get me decent medical techniques and a ticket to the Moon.
In general, I don't know when inspiration will pop up.
If one must explain a magic trick, one should do so after the show is over.
And every friend I've got has been writing Mars stories. It was pretty clear I'd never catch up.