You'll find that the first few times you'll have a hard time not because you can't do it but because of the "real factor". If you keep it in your mind that you not flying the real thing but the sim you'll over come you nerves. For example the piro flip, I could do it on the sim but not in real life till I just imagined I was flying the sim , and I did it. Now that I'm very proficient at nose in allot of maneuvers come very easy. For the the sim gave me the starting point or the feel for how a maneuver should go , flying it for real enforced it on my mind and helped me proficient it. Now I don't even fly the sim I feel more comfortable flying the real thing.

The most important thing is to learn nose in and ALL attitudes of the helicopter. What I do once and a while is hover the helicopter in one place as I walk around it while the heli hovers in one direction. This way I see all attitudes of the heli , then you do the same while inverted. Like Curtis said "once you learn the basics 3-D flying comes easer and faster".