I would try to keep the "rewards" to non-object type benefits. You don't want to teach your children they can be bought for doing good things. Instead make the rewards something emotional, spiritual, or otherwise. For instance, more one-on-one time with one or both parents, an extra story at bedtime, a trip to a park, lots of extra hugs and kisses, playing games with him, etc.
and I definitely agree - only reward the positive, don't punish for the negative. it's a lot easier to have a happy baby laughing by doing things to make him laugh, than to tell him not to cry, right? Peace!!!