How do I prepare for my amnio?

Read re risks, rest. Plan ahead. Take the day off work to relax before and after the procedure. Arrange for a sitter to watch the kids so they need not go with you. Find a friend to drive you and perhaps take you to eat afterward. Above all, discuss with partner, ob, genetics counselor. In advance, the risks/benefits of having the amnniocentesis and what you might do with the information. See my other answers on amnio.
Emotionally. Emotional preparation would be my main advice to you. Otherwise, the procedure is pretty painless and quick and should not require much preparation on your part.