I have been flying an aerobird 3 channel elec. and wanna go to a aileron plane. Everyone scares me with how hard it is to fly, but on G2 I can fly very well, land and all. I'm no expert but i surely can handle all the planes and not crash them too often. Should i get a alieron plane or a trainer?

Get a trainer with ailerons.

G2 can help you out alot with the general knowledge and stick movements. However it is not the real thing. Once you get out there, smell the nitro, feel the breeze and know that it's for real with no reset button. Things happen pretty darn quick.

Is flying hard, I don't think so. My buddy tried to fly my plane, he though it was very hard. My 5 year old daughter flew my plane, she thought it was fun.
It all depends on you coordination and what you know about flying. Sounds like you should't have any problems with a trainer or maybe even a "second" plane. ( CG Tiger II, 4star, do a search for "second plane")
If you already have the basics then a trainer might get boring pretty quick.

What ever you go with get some help for the first couple flights at least. Then you can crash it on you own