I praise everything, good walking, good staying in the middle of the path, excellent teeth cleaning today, clever boy holding mummy's hand. I'm a music teacher so I am skilled at finding something good to say at least 3 times in half an hour! I had a boss who didn't say anything nice to me for 2 years and I ended up throwing my own tantrums out of frustration, so I understand how it can happen.
Less nice things (biting, throwing toys, second cup of water tossed out the highchair) I lift him up (he loves to walk) and pop him in his cot silently. Then I say matter of factly "we don't bite/throw things/etc in this house" and leave him for a short while. I don't give warnings.
I can hear him in his cot saying "no throwing, no throwing, no biting in house, no biting mummy, sorry now" and then I go in and we do a different activity.
I'm like Aloha, I don't expect him to leave the park without the promise of something better, but at the moment going into his car seat seems to be the bees knees.
I always make him help with putting away toys if he wants to play with a new toy, can't have lego and little people out at the same time we'd break our necks. I put his last toy away for him at night after he's gone to bed. You can't do this stuff when he's tired and past it.
Ds hasn't worked out that those car things in supermarkets go. He just sits and twirls the wheel until I ask if he's ready to "help" with the shopping.