Please, my own opinion, no shock collars, no wumpin's.
They are intelligent creatures and just like little kids....you leave a three year old in a room for more than a split second and they don't like that - then you get purple marker on your carpet (heh heh).
They learn and live like kids...no one is perfect and some, unfortunatley, are just trouble-makers.
I am just lucky, I suppose that my dog (Shep cross) is the sweetest, most loyal, laid back dog I've ever had. He is so much a family member I really think I should be able to claim him on my taxes!
Sorry...got off track.....as far as training goes. Barbara Woodward has a few good ideas. My own way of thinking....teach them who the alpha dog is....(um by the way, that's you!) because they still, no matter how domesticated, think in the pack aspect. You are the boss....that never means you have to hit them (that is a nasty human trait) but you have to develop the "pecking order".