A few things I have found to make helicopters easier:
1) A stick with no center detents, since you will be making very small corrections around center. The MS Force Feedback 2 was great for this. Now I use a Saitek X52 Pro, but I have zip ties on the spring so the centering plate just slides around. (This makes it impossible to trim a fixed wing, though. :d)
2) A decent rudder control. The FFBk2 had a light twist grip, and worked pretty well. The twist grip on the X52 is way too stiff, and makes small smooth corrections very difficult. A friend of mine uses a Thrustmaster Afterburner HOTAS, and the rocker on the throttle isn't too bad. I ordered Saitek rudder pedals yesterday, so I will have to get back to you on that.
3) Collective. The throttle lever on the FFBk2 was a little small to be precise. The throttle on the X52 (detents removed) works great. It's even more realistic if you strap the throttle to the side of your chair and reverse the throttle axis in the sim, so you are pulling up to go up.
4) Situational awareness. You can't get a good feel for movement by lookng straight ahead, especially if you are more than a few feet off the ground. TrackIR has made a world of difference -- I can't even begin to describe. If you don't want to spend the money, there is also Free Track:
http://www.free-track.net/english/ And don't forget to watch your instruments. I find the VSI and airspeed indicator to be by far the most important instruments in the heli.
5) Practice. (Of course.)
6) Go nuts. In real helicopters (and radio control) you need to be able to hover before you can fly. As simmers, we don't have that restriction. Years ago, I learned how to fly by grabbing a handful of collective and yanking and banking (hey, I was a kid!) At higher speeds, the helicopter flies a little more like an airplane, so the control movements will feel more familiar to you. If you can maintain level flight and smooth turns will full collective, well you're that much closer to being able to control a heli. So if you get frustrated trying to hover, take a little break and burn up the sky for a bit.
Hope this helps. Good luck!