RE: RC Ken and MinnFlyer have joined forces
I learned to fly helis before I learned to fly planes. With lots of simulator time and a good set of training gear, I managed to teach myself to fly a .50 sized nitro heli. Since you start off hovering a heli low with training gear, it's relatively easy to teach yourself to hover, and then to fly. With an airplane, the hardest parts to learning to fly are the take-off and the landing, and you have to do both on your very 1st flight if you want to have a 2nd flight with your trainer plane! Because of this, you really need the help of an instructor to start with planes, or things can get very expensive and frustrating!
Another thing to consider when first starting out: Helis require more $$$ for equipment (6+ channel computer radio, gyro, high-speed tail servo, high torque cyclic/collective servos, etc.) to get started compared to a trainer plane (4+ channel radio, standard servos). Helis have a steeper learning curve and more of "pucker factor" when you are first starting out. You can't really just relax and fly around like you can with a plane, you are always trying to keep the heli upright and in the air!
After helis, planes came easier for me for the following reasons:
1) I spent several hours on my simulator (originally bought for heli training) flying planes
2) I learned how to set up an RC radio system and tune a nitro engine by flying & setting up my heli
Other than that, planes and helis feel quite different, IMO.
The best thing you can do right now is look up some local airfields (see the AMA website), visit them, and meet up with some of the guys there, especially the instructors if there are any. Then you can pick the field that you feel the most comfortable/welcome at, and get some advice from your future instructor. If you get a trainer plane that he's comfortable with, things will go much smoother. You might even find a flying club with trainer planes available for initial flights (like my club), or a club member with a used trainer plane that you can get cheap!
Best of luck to you! It's a fun and addictive hobby!