As previously stated, know what you're talking about - make sure that the information you give out is correct.
And as also previously stated, the What's New? button can be really nice, but it often shows a whole lot of random threads.
If you don't want to open a thread that's already locked (and/or QA;TL'ed), then look on the right of the page, and see if there's an image of a padlock, if there is then it's locked already.
Edit: felt like typing more.
Look in the General Support section perhaps, and also the Community Corner and Off-topic sections. General Support if you're in the mood to answer some questions, and Community Corner for some friendly threads such as "Hi, I'm ___" etc.