Welcome! Here are some things I had to figure out the hard way:
-don't use a task killer. don't kill tasks
-the stock Email client is buggy and lacks features. Try K9
-the stock browser doesn't have tabs and you cannot have the user agent stay on desktop/computer so try Dolphin HD and xScope. Opera Mini is another browser that can be useful because it allows uploads, works when other browsers don't, and is really fast
-watch out for the GPS icon in the notification bar at the top. It really uses battery power. When you are done with Navigation, choose Exit from the menu. When done with maps, press your phone's Home button to tell it to stop using GPS
-when installing apps, watch what privileges you are granting! Why is your wallpaper asking to access your contacts? Also watch for stuff that runs on startup, including widgets, which can take a toll on battery charge.