Before I had any money or airsoft experience (Not that I have much more of either now...)
I bought a cheap KJworks GBB pistol.
I played with that and 6 mags and it really taught me how to play.
I used to use a JG M4, and it felt distictly easier after having played with just a pistol.
So, GBB may have been harder to use, but it really helped me learn tactics, as well as how to conserve ammo.