I assume farmer/farmhand is number one. Please correct me if I'm wrong. When thinking of popular representations, I can think of many options for slave women. Nurse, cook, maid. For men, after farmhand, the only popular representations I can think of is butler, and there can't really have been that many of them, right?
Some slaves were taught trades. There were blacksmiths, coopers, and wheelwrights to name a few.