This is what worked for me

1. Don't think of contractions as pain but intense sensations (I realise you've birthed before but through Calm Birth classes I heard of many women this worked well for in subsequent labours). Understanding the basic physiology of birth really helps too (there is a chapter in Dr Marsden Wagner's book below that explains this brilliantly). The different hormones and the way contractions actually work (3 ways) really helped me understand what was happening to my body during contractions. It removed fear and hence the tension that comes with fear and which can cause pain. This worked in the lead up for me and while it was intense I didn't feel pain per se.
2. If you want the best opportunity to have a drug free labour, have a birth plan in place that clearly states no one is to offer you pain relief during labour at any time. State clearly that if you want it you will ask for it. I also included that if I did ask for pain relief my birth team were to make some gentle suggestions like - why don't you try so and so for half an hour and see how you go, or you are doing so well do you want to just give it 30 more minutes and see how you feel then. etc.
3. Practice deep slow (yogic) breathing in the months leading up. Focusing on my breath made them seem shorter and helped heaps.This is all I used in an induced labour.
4. As you say water may help, I personally didn't need or want it.
5. Practice birthing positions prior to birth so they come more naturally on the day.
6. Embrace the experience as something to be celebrated and ensure you have a great birth team are there to support you not rescue you during a normal birth. Having relaxed, gentle caring people present was a godsend for me. No loud noises, no talking and a dark welcoming space really helped.
7. I went into my cave (the toilet) during transition, sat on the toilet and went with the flow. It was a lovely safe space. Feel empowered to birth where ever you want regardless of anyone else.
8. Read Ina May Gaskin's "Guide to Midwifery" and/or Dr Marsden Wagner's "Creating a Birth Plan". Both fabulous books making the understanding of birth so easy and obvious.

I'll come back if I think of any more things.

I hope you have a wonderful birth. xx