Mmmm, Clubber has already posted my favourite tips. Particular plus one for Naughty Step, with a 'minute for every year old they are' guide for how long to leave them between reminding them why they are there and that they might want to apologise. (any longer and they may forget what they did wrong and then what's the point...)
And the high shelf thing is also good.
Ridethelakes, are you planning on any more?
Parents need to be even handed in their approach both between what mum does and what dad does, and also to each child. In my professional life its amazing how many kids I meet who can't do right for doing wrong, and have some amazing sibling from whose behind the sun shines. It can be a hard pattern for parents and their kids to get out of.
We started very basic reward charts at late 2's early 3's, but that was more about taking responsibility in a positive way for small things rather than 'not being naughty'.