What professions can be called 师傅?
Taxi / Bus driver 


"师傅, 我要去天安门."


all the manual workers


  "师傅, 我想做一个木头大象"


"Mr.Carpenter, I wanna make a wooden elephant."



  "师傅, 你能搬动大象吗?."


"Mrs.Porter, Can you lift an elephant?"



  "师傅, 我要给我的大象烫个头发"


"Miss Barber, My elephant needs a perm"


Note: not used in high class barbershop


  "师傅, 我不是坏人"


"Mr. Entrance Guard, I am not bad."


In real life, there are some native Chinese call doctors, teachers 师傅, not much, but it really does, the doctors and teachers said they don't know if they should laugh or cry, embarrassing, since in practice, 师傅 are always applied to these professions that do not need to learn from in colleges.

Note
You call one 师父 who teach you some professional skills.