Initially go high and drop on to the target. This works well but you are a target for aa mines. However the location of an aa mine also is the location of a target.
Once you are confident with that approach practice the daisy cutter approach. This means flying low, just above the ground and taking out targets at ankle level. Main thing to remember is that you need to gain a little bit of height before turning.
If you get this far then the next phase is going through objects, doors etc. In most cases you can, with some practice go almost anywhere. The tower on Zavod is hard to go up the stairs but most other places are doable as the round progresses and walls are taken out. It is possible to go down below C on Zavod and back up out the other side. Inside locker is possible too. You can get quite a way in through the entrances near A, D and E.
The best hunting grounds are:
Roofs: Zavod, flood zone are obvious places. Shanghai tower is good both on the roof and also inside (get up there early and take out all the windows)
Caspian is good once the tower is down as you can usually get a few running up or down the tunnel. The lookout posts along the wall are doable too.
Locker - fly low and you are almost certainly going to get someone running outside
The more open maps need you to be a bit closer to the victim as you can use all your power getting across the map.
Firestorm - quite an open map but the mountains and tower are usually well stocked with potential victims
Multi kills are possible. You can quite often get a twofer if they are lined up. Be prepared to have a chance to get another victim. The best one is when you get an early roof kill on flood zone and they have a beacon. You should have enough power to do a go around and get them when they spawn again. (Mute chat at this point).
You can keep vehicles amused for a while when you lock on to them.