Last week Google released a new version of the Android Development Tools (ADT). If you've not updated to version 11 yet, then DO IT NOW! There are a number of big improvements that will enhance your app development process, particularly regarding layouts and XML editing. Take a look at the video below for details of the update made at Google I/O 2011, if you've been developing on Android for a while, this should really get your juices flowing!
If you're not already then you should be following the Android Developers Blog (or @AndroidDev on Twitter).
How do update my tools in Eclipse?
Make sure you are running Eclipse as Administrator, then go to Help > Check for Updates.
Now just step through the sequence, agree to license terms then restart Eclipse when prompted.