I guess the first question is what airplane are you using to practice 3d?

Foamies are nice if you already have the electric setup. I am learning 3d right now and I first bought a .40 sized mojo (considered one of the best 3d trainers out there) and even that was a bit too unstable for me, so I moved up to the .60 sized mojo which is absolutely perfect for learning 3d...everything is extremly stable.

Some things I've personally found to help me learn 3d (in order of importance):

1. Fly the right type of plane which is set up for 3d aerobatics
2. Fly with someone that is a good 3d pilot
3. Make sure your throttle transition is quick and you have a very reliable engine
4. Practice harriers (Plane still moving forward but slowly.....helps if you have the plane pointed into the wind)
5. When learning to Hover, practice LOW to the ground...like less than 10 feet (foamies help with this...cheaper)
6. Get VERY comfortable flying knife edge on BOTH sides and be comfortable switching from one side to another.
7. learn how your throttle can be used to keep your plane stable in High Alpha situations
8. Your rudder is your friend
9. To help with wing rock, adjust both left and right ailerons up about 1/4 - 1/2 of an inch
10. Adding in a mix that slaves your ailerons to your up elevator (only about 10-15%) helps stabilize a hover (this causes inverted harriers to be more difficult tho)

The reality is, it's not very easy to learn 3D.....it takes a lot of practice and a lot of fuel / batteries.....after a while, your muscle memory will start to kick in and you will stop thinking about it.

[link=http://www.blaineaustin.com/3d_tips.htm]HERE[/link] is a great website to describe 3d.