Gavin, I'm a new smart phone user too and have the same phone from windmobile and the first thing I noticed about the phone was how quickly the battery can drain. I thought it was defective or something but no, that's how it is. Mine would be dead from a full charge in less than 14 hours and that's without any usage, which is shocking and made me consider cancelling my plan. I do have data running however. Anyway, there are a bunch of apps available that can preserve the battery life. I've tried 3 or 4 and the last one (just found it 2 days ago from the Play Store) is the best by far. It's called "battery defender". I fully charged my phone yesterday and after a whole day (24 hrs) I checked the battery status and it showed 90% left (the app adds a battery icon that shows % left). Pretty damn good for a phone that used to be dead in less than 14 hours. I'm extremely happy. You can also try "juice defender" (the first app I tried) but that will probably give you 2 1/2 days on a full charge, which isn't bad.
BTW, draining and charging the batt won't do much if anything at all and in fact it ISN'T recommended that you let it drain below 20%.
Check out those apps and download one. They're free and they DO work. Also, get yourself a car batt charger too and maybe an extra battery.