The best thing to do is farm floor 201 over and over until you get enough dust and crystals to build a floor 500m3 farming build. Use that to farm create one of the floor 1k+ builds posted since 3.0 to climb further. This game gets real easy once you can farm crystals efficiently
This post has some great hints
Here is a pretty decent farming build
There are at least 10 builds that have been posted on the forums since patch 3.0 which can climb past floor 3000 on mythic 3 difficulty. Copy their builds or borrow concepts that you like to make your own. Just make sure you have crushing flames and at least 30% crushing blow.