One of the worst things to do if you get a bite from a bird is to react, I know that is very hard to do but if you don"t you may actually be reinforcing the behavior. Birds love attention its not surprise there, so if your bird bites you and you scream they will most likely be like "ooo this is fun i get attention" or "i can get them to stop if i bite" so if you get a bite simply don't react, stop what you are doing and think back on what you were doing. Maybe you were ignoring the signs was the bird not wanting to step up but you made it?
Myself and my family have greatly reduced the the bites we get by following the 2 simple steps of not reacting ( screaming) if we get a bite. Lastly watching for warnings that the bird does not like or want to do something. Warning signs can be somthing a simple as pining of the eyes or raising of some feathers.