I have to tell you guys, I'm going to get this on a clipboard so I don't have to keep retyping it.
Do not expect great battery life from a Droid, or for that matter most smart phones. They such up a lot of battery.
You can go ahead and try dimming the display, turning off blue tooth, wifi, etc. I don't think you will see much difference. And updates to improve battery life? Well, I've seen a few come through which specifically said it was part of the update and I have noticed no change.
So like I have told many others the best way to handle this is to get a spare battery, inexpensive at amazon.com. Under 10.00. Get a charger from ebay. That's about 5.00. Use it a lot in your car? Get a car charger, those are probably more expensive but if you need one then get one.
What's the point of having a smart phone if you're constantly worried about battery use. A small investment is worth the piece of mine.