Normally I look at the profile of the person to know more about it and know how to start the conversation, an example of that was that in my profile I said I did not like chocolate very much and a boy asked me why and so we started a conversation.
What does age matter? I really consider it not important, what matters is that there is respect between the two parties. Now, some messages that seek to hack your account may arrive, so you should avoid it. He also avoids asking questions about his Rl, many people in SL do not like it and also because there are certain types of questions that should only be asked and answered when there is enough confidence (by this I do not mean something sexual).