After three births, I've learned a few things, at least about myself. One is that no two births are the same, and another is that a natural childbirth isn't something that just happens (usually), but must be prepared for (and of course one can't prepare for everything, and sometimes a natural birth just isn't possible).
Perhaps the most important factor, in my opinion, is having the proper support. My husband has been invaluable at my first and third births (he was unable to be with me during Charlotte's birth because he was taking care of Kieran). Even so, I did not have the completely natural, drug-free delivery I wanted with Kieran because I was not supported by my midwife. When giving birth in a hospital, it's impossible to know if you'll get nurses/doctors/midwives who are supportive, so I wish I'd had a doula for Kieran's birth. I'd like to think that I would be able to stand up for myself now, given my confidence now, but I can't say for certain since I never know how much I will be able to express when in labour. Besides, I'd rather not have to fight anyone when in labour. The midwives I had with Charlotte and Leo, though, were very supportive and ensured I had the birth I wanted (ie: as hands-off as possible).
Support, while invaluable, isn't necessarily enough. One must be mentally prepared and know about various techniques, I think. With Kieran, I had the relaxation/breathing down, but hadn't looked into various positions to help with the back pain and such. I'd gone in fixated on having a water birth, only to find the pool wasn't available until I hit transition, when I no longer wanted it. With my other two, I've had ideas about what I'd do for relief, but I didn't lock myself into that. I really thought I'd want to labour under the shower with Charlotte, only to find that I didn't want to leave the birthing ball. I'd planned on trying for water birth again with Leo, to find I once again wanted the birthing ball until transition, when kneeling on the bed seemed like a good option.
I think the mental preparation is also good if you don't want the drugs. I know I can't have the epidural, so it's not on my register at all. With the home birth and birth centre birth, I knew other drugs weren't available, so I didn't wish I had them. Also with the birth centre birth I knew I couldn't ask for nitrous, so again it wasn't in my mind. Instead, I knew I had to get through it using various positions and counter-pressure, and so I did.
An option I've not considered but which others have liked is hypnobithing. I don't know enough about it to discuss it in detail, but I have heard good things about it.
While not strictly necessary, I'd also recommend having red raspberry leaf and nettle teas in pregnancy and labour and after; red raspberry leaf tones the uterus, and nettle tea helps with bloodless, being hi in iron and vitamin K. Coconut water is fab for balancing electrolytes after, and I'd imagine is good during labour, especially with a longer labour and/or if a woman's eating is restricted (another reason I'm thankful for my midwives, as I was eating throughout labour).
So to sum up: research different positions and coping strategies. Don't lock yourself in to just one strategy. Get a birthing ball, because even if you don't use it in labour, it's good in pregnancy and after. Find a supportive provider. And realise that every birth is different, and that sometimes circumstances don't allow for our plans.