Do your GC turn in every day - and try to get HQ if at all possible. It's slow but it's a steady 1/4th-1/3rd of a level every day. I also /highly/ recommend leveling gathering first, doing it the other way around is very cost prohibitive and will make you want to scream as I learned the hard way. (To the point I've been dragging my feet about leveling crafting on this character after doing it on my old main.) Once you are at the level to do so, start doing collectibles, and between that and leves/beast tribes you'll eventually get to cap.

Grinding is pretty good for gathering classes at lower levels. I'd just pop on a movie, especially if you're leveling fishing, and go to town. Don't forget the manuals you can get from your GC either, or company actions to impart more exp, they'll make the experience a lot less painful.