How to stop a nippy dog

I have a 1 year old lab/ sharpei mix that has a nipping problem. Whenever he wants attention he’ll nip at my hands or any body part he can get to. I’ve tried ignoring it to make him stop but it only makes him more aggressive. I’ve also tried putting him into a timeout but he just continues as soon as he gets out. I’ve even tried rewarding him when he’s not nipping but nothing seems to be working. I would appreciate any help