[MENTION=3417]pedro.ochoa.urrea[/MENTION]
Welcome, thanks for saying hi. When you ask people here how they got really good at 3D, most of them will tell you that they are still trying to get really good at 3D!
The flight simulators are really good for practicing basic orientation like how to use your rudder while inverted, get the plane to go where you want in knife edge, etc. There is no telling how much an average flyer needs to spend on the simulator because you make the most progress setting up real models and flying at the field.
Look up "Bonedoc1" and "Wamsy's 3D tutorials" on youtube. Also, read [thread=228]Ben Fisher's 'How to land a 3D plane'[/thread].
Other than that, be sure to ask anything about specific maneuvers you're having trouble with.