My one year old hits, bites, pinches, and scratches! HELP.?

My one year old (well, hes almost 15 months) likes to hit, pinch, scratch, and bite. Oh and pull hair. I've tried everything. I tried time out, didn't work it absolutely did not bother him to be in his crib or playpen for a minute. I tried slapping his hand at first (I DO NOT do this anymore since obviously I made it worse by teaching him to hit). I've told him firmly no, shook my head no (which he associates with no pretty well) he just either laughs or hits again. I've tried seriously everything. Telling him "No baby that hurts mommy" to acting like I'm crying to yelling at him. I just don't know what to do. My babysitters don't want to be around him. He's mean! Please help.