I've been meaning to start this thread for ages (DC2 is now 17 months!)
My birth with DC1 was straightforward but quite painful and I am a bit of a wimp with a low pain threshold. Had an epidural and thought it was marvelous. Was completely up for an epidural the second time around and have never really put much stock in e.g. yoga or breathing to make a difference in childbirth (although I'd been to all the classes because I'll try anything...).
Anyway, I read a post by someone on here about breathing in labour where they said that what had really helped them during contractions was to take a deep breath in and then to breathe out really hard as if trying to blow an imaginary spot off the wall or floor. I'd never had a breathing technique described in that way and so I tried it during my second labour. As it turns out, my second labour was more painful than the first (because of the speed - I went from 2-10 cms in under an hour) and I managed without an epidural because that breathing really did make a difference.
I wish I knew who it was who wrote that so I could thank them. But I don't, so instead I am just repeating the advice here in case it helps anyone else in the way it helped me.