Answer:
Well, when i used to be a teen, many of my friends (and ill admit myself), went through puberty, and that makes you very moody at times. Also,teens these days are under a lot of stress and pressure to fit in. So basically, you just have to not annoy them, but be there when they need you. Because you never know when you'll be bossy to them, and need them to be understanding. Put yourself in their shoes and see how you'd want them to react to you being bossy and try doing the same.
Answer 2:
Most of the time, adults will assume that they know more than you simply because you are younger than them. This is true, most of the time, just due to the fact that wisdom comes with age. However, a lot of the people who feel 'compelled' to tell you what to do, just don't know what they're talking about!! A lot of people are just trying to be helpful, or feel useful.
Try to consider what they are saying for a moment. It is possible that they are right.
If they are just wrong, disagreeing publicly will usually get you nowhere. Most people when disagreed with will just repeat themselves louder, as if that changed the situation. I find that most of the time 'sincerely humouring' them will get them off your back, although you still may have to distance yourself from them in order to stop them from repeating the same thing over and over again. Sentences like, "hold on, let me think about that," "That sounds reasonable, I'll try that," and "Thanks for your advice," should buy you some time.
A lot of people are just looking for that little bit of respect and thanks, and when you give it to them, they will usually bask in their pride as opposed to continue to harass you.
Depending on who you are dealing with, this may not work either. If so, you may have to ignore them (eg. deal with it), laugh at them, or politely disagree with your specific reasons. There isn't a single method for dealing with all people; you'll have to figure out what works best on everyone.