My first was induced, so my DH and I wanted to be part of this birth!!

I did a couple of meditation/relaxation sessions with my doula, and she taped them for me and when I couldn't sleep I would put the headphones in and listen to them at night (usually sent me right off!)
I know she said lots of positive affirmation things, and lots about seeing the contractions as bringing my baby closer (not as pain to retreat from).It must have worked because I was in the bath falling asleep between contractions for about 2 hours at the beginning. I had a very relaxed approach over all ( not like me at all! I just wanted to die with my first baby, if I had been able to jump out the window I would have...but that's another story)
I also had some music that I liked which DH put onto a CD for me and we played that for a while as well, it was a distraction, it was music that I play when I feel happy but quiet, so it was supposed to be all "mood inducing" I suppose!
I did use gas, but that's because it worked for me, to focus on the breathing in between contractions - my husband sat and counted from 1-25"Ok contraction coming breath gas" to 35, "ok coming down, gas stop" to 60 and over again for about 2 hours! For me it was quite hypnotic and certainly felt more like 15 minutes!

You've got 20 weeks to go, more than enough time to get yourself mentally prepared which is such a HUGE part of giving birth. Perfect time to start!