So, I'm going to teach you how to get on top of the middle arena in Gadgetzan, pretty good spot if you know how to "use" it well.
Alright so first things first, get yourself to Gadgetzan, Tanaris, whatever you refer to it as. Then, go to the middle arena thing and walk around until you see 3 (THREE) boxes together. Go in between the ones from the middle and right one, and then jump, and tap forward. It seems to work better. This takes a bit of practice to get right, but now it's pretty simple. So now your on the middle box of the three. Go to war with Gadgetzan, and wait for a moment where there are no guards in site(except for one that is stationed in front of you). Now, attack him with some ranged attack, you can mana shield or whatever here. He'll start aiming at you, so get ready. Face him, and your back towards the arena, and jump about when the bullet comes at you. You should get flung backwards in the air onto the arena. From here, you must shake off the guards using whatever method you prefer. This is my hardest part, you can run in circles, try and get out of LoS, etc. I'm not too great at that part. Anyways, from their you can gank pretty well, just try and avoid guards.
You should be around levels 53-55+ depending on your class, so you don't get pwnt by the guards. Anyways, enjoy this guide, hope it can help you in some way.
Jimminy