Rodders really doesn't like being stopped from doing something he shouldn't and quite often tries to bite me when I tell him off. This is something that I have struggled to deal with. On the odd occasion when he has actually managed to make contact it flipping well hurts and it is alright if he does it to me (well, not really) but so much worse if he does it to someone else.
I have tried a firm no but it just makes him worse, I have tried tapping his nose and saying no and I have tried holding his head and making him look at me as I say no but nothing seems to work. For the last 24 hours I have put him in the kitchen behind the baby gate when he does it and I leave him there until he stops barking or whining and then try to get him to sit and say sorry by licking my hand. This has had some success.
But I really wish I knew how to stop it.