Be observant about everything. If something isn't working, no matter how small, /bug it. When making your bug reports be as detailed as possible. Also, don't hit your enter key to start a new line. I guess it makes the reports really larger. Just go with run-on sentences.
Crafting and Diplomacy really need attention from testers. That is where a majority of bugs seem to be showing up. (At least, right now)
Last, and certainly not least, have fun. We are a very helpful community and we enjoy sharing. The best way you can repay someone who helps you is to pay it forward.
See you ingame!!!