How can I effectively Discipline my one year old?

Hello, I have a 14mo old baby that has started hitting evryone be it on the arm the face ANYWHERE he can reach. Along with this new act hes also throwing tantrums by screaming at the top of his lungs for LONG periods of time. We have tried telling him to stop by saying "hush" or grabbing his hand and saying NO when he hits but it hasnt gotten better. The bad part about that is that now evry time he hears NO hell throw a screaming fit so its made it worse. I was told a slap on the hand should help but im assuming hell only see that hitting is okay and keep hitting others himself. Im STUMPED. Ive gotten to the point where I hate going anywhere because his screaming. Any advise from experienced mothers?? Thank u =)