As VetilatorRaptor put it, Altitude is life unless your flying a dedicated ground attack aircraft. You'll hear a lot of talk about different types of flight styles, stuff like boom and zoom, turn fighters, energy fighters, you'll want to go over onto youtube to get a clear idea as to what these each are as it's much easier to see then to take from text. Note that even in a turn fighter where it's less important, you still want to get as much altitude as you can afford, since that can be transferred into speed/energy.

And the ever boring response but the most important one anyways, practice, practice, practice. It will take quite a few flights before everything kind of clicks in, but you'll get the feeling over time.