Any good ideas, how to teach my 3 month old NOT to bite

She is a Border Collie,Pointer,? mix. She left her Mother at 6 weeks. It was too early, but couldn't be helped. I have given her chew toys, Rawhide chewbones, small tennis balls, to chew on. She still jumps up on me with her front two legs, and bites and mouths. Her teeth are very sharp, so it is painful. I don't want to punish her, but she needs to learn not to do this to people. So far, I have only sternly told her NO! And DOWN! With a hand signal of my hand moving from shoulder height, quickly down to my thigh, pointing an index finger down towards the floor.If anyone has any positive suggestions for training her not to do these two bad habits, in a humane and effective manner, it is greatly appreciated. Thank you.

Uh huh.well, she doesn't quite understand what NO and DOwn mean - unless you have taught her "down" already.

Ignoring does not work - they don't know the difference between being ignored because you disapprove of the behavior or because you are trying to the house cleaned. Spray your hands?? How long are you supposed to walk around smelling funny, eh? Distracting is really dumb - she jumps and nips and you give he food or a toy - that is called "rewarding the behavior." One of the current weirdest theories is giving the dog a "time out" - what, they are supposed to sit in their crate or pen and THINK about their sins ? Sign that dog up for Harvard if it can do that! Just holding their mouth closed is an invitation to keep playing the game. Another one that just esclates the fun - from her point of view - is pushing your hand further in her mouth.