Oh, another physical thing I forgot to mention...close your 'waki'...in english, the best way I can describe it is to keep your armpits closed. Perhaps Peter Goldsbury or Jun can give a good description of this. You also seem to need to be mindfull of where your elbows are in relation to your body.
Another factor I didn't speak about is the need to develop the ability to absorb or neutralize your partner's energy. There is a thread that speaks about this a bit here: