1. The big beautiful screen - Its the biggest phone screen on the market (unless you count the Galaxy Note as a phone, I think its more of a Tablone.) Its HD and packed with pixels. It uses a lot of power when its turned on. The best thing you can do for battery life is reduce the brightness as much as possible. I keep mine at 10% unless I am outside or in a brightly lit room. Its plenty bright for me to read 90% of the time. I use a power control widget, widgetsoid specifically, on my home screen to give me quick access to adjust the brightness. I find Auto Brightness unreliable and I think it tends to set brightness higher than needed.
2. 4G data - That's right, all those G's come at a price. With the current 1st generation 4G chips comes some inefficiency. While 4G should technically be faster and more efficient than 3G, only the former is true. Until we start seeing some of the newer 'Hybrid' 3G/4G chips, we'll have to deal with the inefficiency of running multiple chips.
So, what to do?
USE WIFI. As much as possible. In terms of battery usage WiFi < 3G < 4G. So turn it on and use it whenever you can. If you are in a weak 4G area or have no 4G where you are, turn it off. (settings > more > mobile networks > network mode > CDMA). If you go in and out of 4G areas and want quick access to these settings, your best bet is a widget called 4G Toggle which can be downloaded from the Marke....sorry, the Google Play Market.
3. Talk Time - Yup, in the world of email, Facebook, texts and IM's people tend to even forget that their phone can make calls. And in fact, voice calls require quite a bit of power. I'm not trying to discourage actually speaking to other human beings, rather just letting you know that it does drain your battery fairly quickly when you do.
4. Sync - WHAT? What's the point of a smartphone if it doesn't sync? That's true, just be smart about what you choose to sync. Every sync wakes up the CPU and uses your data connection and thus some power. The less you sync the better your battery life. So let's talk about what you NEED to sync. Personally, I sync Gmail, Calendar, Contacts, Browser and 1 pop email account every 30 minutes. No Twitter, no Facebook and no Google+. Firstly, Google+ is a known sync hog and would sync constantly causing a noticeable battery drain. Second of all, do you really NEED to sync things like Twitter, Facebook and Google+? Do you NEED updates constantly? Not really. When you open each of their apps within seconds you've got all your feeds updated. Get your social media updates as needed not as posted and you'll save yourself some juice. Oh, and I'm pretty sure syncing your photos tends to be a drain too but most people probably use that feature and can live with it, but I thought I'd point it out anyway. Some people report problems with Google Talk, but I've had it on and running since December with no impact on battery life.
5. Streaming - It should be obvious, but in case it wasn't, streaming uses data. Data uses power. Therefore streaming drains your battery. If you listen to Sirius or Pandora, or if you watch a lot of YouTube or Netflix videos, expect to see your battery drain quickly. Especially for videos since you've got the double whammy of data and screen on.
6. GPS - While receiving GPS signals alone doesn't take much power, note that Google Maps/Nav has to be connected to data to work. So it will maintain a constant connection to identify your location and track you on the map....even if your screen is off. If you could cache your route and the maps offline and run without data it'd be fine, but until Google implements that you are SOL. GPS Navigation is a HUGE power drain especially if you have the screen on. Many users report that their car charger cannot even maintain a steady charge while using GPS. This is not unique to the Galaxy Nexus but is a 'feature' of the way Google Maps/Navigation works. This won't change so long as Google Nav works online.
