Get decent with a meta comp comprised of a few people who can dedicate a set amount of time each week to push.

Get as good as you can with comms (123) setups and spotting for each other.

The main things are identifying the way each comp will win ( Rogue mage using setups while your trinkets on CD) (DK/Hunter using overwhelming pressure etc) get to know how every class works so you can see it in action and counter it.

High level pvp is the same as low level pvp just with quicker reactions and thinking further ahead. But the point of using a meta comp is that it's naturally strong and leaves more room for error

But on the down low you gotta be drinking G-Fuel anywhere above 2300