First of all, somebody may only have up to two elements at a time, if combining those two elements creates a third so be it. The first element comes at genin while the last comes at jonin. You can have as many jutsu as you want, following the guidelines. Since we do not like to have somebody who is epic at everything, please refer to specialties in guides an info for other rules dealing with jutsu or specialties in any way.
Academy students: Can only learn D-rank jutsu at the highest.
Genin: Can only learn C-rank jutsu at the highest.
Chunin: Can only learn B-rank jutsu at the highest.
Jonin: Can only learn A-rank jutsu at the highest.
Anbu: Dependant on the user characters rank
Kage/S-rank: S-rank jutsu at highest.