There are ninja that choose to specialize in specific jutsu and/or skills from the time they are genin or later on in life. Here are those proffessions, you may only choose one and it must be your character's most common and strongest skill.
Kenjutsu- kenjutsu specialists specialize in swordsman skills. They usually have a lot of upper body strength which allows them to cut through anything the sharpness of their blade will allow. They are also skilled craftsmen which comes in handy when their swords need work.
Taijutsu- Rock lee...Need I say more? Taijutsu technicians specialize in hand to hand combat. They believe that pure fighting skills alone can always win the fight. They are physically strong due to intense training and can eventually learn how to open the eight inner gates due to learning how to release their true strength.
Ninjutsu Ninja that specialize in ninja skills, but of course we all knew that already. These ninja usually travel the world learning more ninjutsu skills as wandering ninja or doing many missions in foreign lands. If you like Kakashi's style of fighting, this is the specialty for you.
nagairenjijutsuthis is the way of kunai's and shuriken and all long range things.nagairenjijutsu is basically the art of using a combined jutsu of long range and ninjutsu.using the stealth of the darkness,you swiftly strike from the shadows using long range
KugutsuThe art of puppet fighting. Ninja who train in this art are normally weak but very intelligent and highly creative. They use life-sized, customized puppets, usually filled with poisons and weapons, to use skills like shooting out body limbs with concealed blades and spewing poisons from their bodies. The puppet master controls their puppets with chakra strings emitted from their finger tips. The more puppets he or she is able to control at one time, the more skill they have. (Being that this style originated from the village hidden in the sand, you must go there and register for it)
(More will be added by admins)