Atlanta
It'll never be totally painless, so expect some pain initially. That's part of its charm 
However, you can minimize the pain by following these guidelines:
1) Do not attempt unless you are fully turned on and very comfortable with your partner.
2) Complete relaxation is necessary. Massage the entire area-- start with a tongue, move to hands, finish off with a vibrator. Guys, my favorite move is to lightly press the whole area with firm and steady pressure. You will feel the muscles give when they are relaxed enough to attempt entry. Don't force it, and don't get eager or you could be SOL. The good old "stretching spread" works wonders here...slow + easy does it! Try entry with the vibrator, or small toys. When this is working *great*, move on to the main event.
3) Use a ton of lube. Astroglide is my favorite and won't harm condoms like oils or vaseline. "The Spit" ala porn movies DOES NOT suffice, and is not safe. Also focus on your breathing, deep, slow regular breathes keep your entire body relaxed.
4) NOW-- what works for me is doggie style, he doesn't move (I repeat--HE DOESN'T MOVE). The initial entry will make or break the experience and any wrong move on his part can turn a mildly uncomfortable experience into a painful one.
First take a deep cleansing breath, then focus on breathing and relaxing. Back onto him slowly, stopping to breathe when necessary. I have found that slightly bouncing back and forth, or moving my hips in little circles eases the process. Keep the lube handy, and use anytime you feel you need it.
Keep moving until you are comfortable, and decide its working out, then let him take over.
5) Practice, practice, practice. It gets easier and more enjoyable each time.
Have fun + hope this helps,
xoxo~Angela
Ohh! Me, me! Pick me!
Very good question FirmOffer! It kind of suggest that maybe someone is pushing their limits; more the just a hobby, its a profession! What a concept!
Joey
You could always try someone like me with a small dick.