Decide what you want. The more idea you have of what you want to sound like before you go into the studio, the more chance you have of coming away happy. Listen to CDs that sound the way you want to, and take them to the session for reference.
Surprisingly, musicians are often not the right people to judge which of their own songs show off their talent best. Ask people who know your set to suggest which are your best songs.
The best way to find a studio is to ask as many musicians as you can for suggestions. A personal recommendation counts a for a lot.
Visit the studio beforehand and chat to the engineer. Even if you're not technical you'll get a feel for the place and the staff and you can make sure it's somewhere you're happy to work. Visit as many as you can before you opt for one.
Ask to hear some of the recordings the engineer's made. See if you like the job they've done with other people, and make sure they've got experience with the kind of music you play.
Make sure your equipment works before the session. Don't spend valuable studio time trying to fix problems. Check all of your cables and make sure that you have spare drumsticks, strings, batteries and other disposable items.
Make sure you know the songs. Rehearsal space is much cheaper than recording time, so sort out your performance before you get to the session.
Everything in a recording studio takes ages. You're much better off concentrating on doing a couple of songs well than over-stretching yourself trying to do too many. Talk to the engineer about how much you can expect to do in the time you can afford.
Remember who's paying. It's easy to be overwhelmed by the studio experience but don't forget you're there to get the sound you want. Don't let the engineer persuade you to do things you don't want to do.
Remember that a recording is different from a gig, so be prepared to adapt your songs. Keep the intros to your songs short and avoid long instrumental passages so that the main parts of the song happen quickly.
You can do a lot in a studio to make things sound better but don't rely on that. Learn how to tune a drum kit - you can find hints on how to do it on the internet. Borrow better equipment if yours isn't great.