Another thing that works great:

Just email one specific question.

Then a week or so later, email another specific question. Repeat.

I've been saying no to all "pick your brain" requests, and even interview requests, but if someone emails a specific question, I answer it. (I'm at derek@sivers.org if you want to test this.)

One guy wanted an interview, I said no (just too busy), so he emailed just one question, then did it again, and a month or so later he posted our interview: http://onepercentcollective.org/derek-sivers-generosity-talk...

I thought that was a pretty clever hack. Clever enough that I then met with him later, and he's an impressive dude.