I usually just go through the "most recent" lists in each category and answer the ones I can/want. I do not prioritize friends' questions. I will, however, answer questions that people specifically ask me to, and some of them have been very old ones. Generally, if someone messages me or asks me a question I will always answer them.
Honestly, I mostly just click on "Answer" and start with the newest questions and work my way backwards until I'm out of time, or until I get to questions I've already seen. I just read the questions and answer whatever is interesting or that I might have some useful feedback for.
2. Questions from people whom haven't made an ass out of themselves and looked like a total jerk
I like behavior and dating questions best. They stimulate my mind without being too heavy with drama like a lot of the questions in the 'Break-up' and 'Relationships' category. I usually only answer the really old questions if I find them very intriguing or interesting.
I don't have any real life friends on GAG, but as far as my friend list goes, I don't really make it a priority to answer my friends' questions unless there's one they ask me to answer and I end up finding more of theirs that interest me. I usually just look at a few pages each of the questions on the Recent, Poll, Top Rated, and Popular tabs. Then I go to my favorite categories, Other, Sexuality, and sometimes Relationships, and look at a few pages each of recent questions from those categories. If I'm in the mood to ramble about a certain topic, I'll just type it in the search box and answer a few questions about that topic.