I think it's really important to think about stuff beforehand and have a clear idea about your preferences. I didn't write mine down - it was all in my head which was enough for me, but if I had written it down it would have been "I want to get as far as I can without drugs. Let me do my thing - leave me alone and if I want drugs I'll ask for them." Which is what happened. Apart from that, I wasn't fussed about episiotomies, 3rd stage, cord pulsating etc. etc. So mine was pretty simple.

I really prefer the term "birth preferences" because "plan" is such a divisive term - you will get too many people saying "oh, it never goes according to plan so what's the point of having one" and others who say "well, if you don't have a plan, you won't get what you want."

Personally, I think it's way more important to plan your pain management techniques - I recommend Juju Sundin's Birth Skills.