My approach (with a strong nod to those like Levon and others):
- ask good questions after putting effort into finding the answer first
- answer questions with just the right amount of detail based on the need I perceive
- be reasonable and polite
I upvote good questions that show some thought; likewise for answers.
I downvote only if I think the answer is improper or incorrect.
In other words I try to make using SO enjoyable for all (and so it will also be enjoyable for me!)

What I use most: Linux (Ubuntu); Python (2.x mostly); C. Also do android Java; iOS iPhone Objective-C.