Helpful:
Hypnobabies, especially affirmations and visualization exercise
Chanting "open open open"
Counterpressure (I had back labor)
Shower
Birth Pool - way better than the shower
Being left alone and not messed with
Being told "You are doing it" when I said "I can't do it/this!"
Having all the birth supplies ready and a list of where everything was kept so the mws/dh could find it during/after the birth
Having lists of who to call right after birth
Not helpful:
Anything DH did, pretty much

Birth "projects" - my labor and birth were far too fast for these. I had a bunch of things I planned to do that never got done (for example, brewing and drinking RRL tea). The things I did try to do, like string the birth beads from our DDC swap, I just couldn't concentrate on - I was too far into active labor.
I'm sure I'll think of more later, but that what came to mind right now