I can't really do much more than tell you how I use SO. I've learnt quite a lot from my time on the site, however, so perhaps it will be beneficial for you as well.
There are three types of questions that I focus on:
- Those I can definitely answer
- Those I might be able to answer
- Those I definitely can't answer
Why am I interested in questions I know I can definitely answer?
I'm not here just to learn, but to share what I've learnt as well - people ask questions because there's something they'd like to learn, and if I can teach them then I should do so. If nobody looked at questions they can answer then no questions would be answered, and nobody is going to learn anything new.
There's also times where other answers to a question I know I can answer show me a better, more efficient method of solving the problem, so there's still potential for me to learn even though I could have solved that problem on my own if I'd been faced with it myself.
Why am I interested in questions I might be able to answer?
Because it provides me with an opportunity to find out if I've fully understood how something works by applying it to a wide range of situations. If my answer is correct, then I can move questions of that type into the "I can definitely answer that" category in the future. If my answer is incorrect, then I know there are still things I need to learn; and, hopefully, there will be comments pointing out my mistakes that will teach me some of those things.
Why am I interested in questions that I definitely can't answer?
It gives me additional knowledge that, while not useful to me right this moment, may be useful in the future. It could be a problem that I haven't come across yet but may encounter in the future or it could provide me with a better way of doing things I'm currently doing.
That's going to make my job easier, because I have a wider range of skills to apply to solving problems, and improve the quality of the work I produce.
Actively participate. Don't just come here when you have a question, ask it, get your answer and leave again. If you have downtime at work or school that you normally spend doing absolutely nothing productive, consider spending that time here instead.
Look at what other people are doing and learn from that. If you see people asking bad questions, ask yourself why it's a bad question, what they need to do to improve it, etc. If you don't know the answers to that straight away, don't worry - if you thought it was a bad question, chances are somebody else did too and they'll probably comment on the question to point out what needs improving. Conversely, if you see people asking particularly good questions, identify exactly what it is that makes it such a good question - then, when you come to ask your own questions, hopefully they'll also be good ones.