I've done a couple of trades successfully before, but you just have to be comfortable with the person and how much you trust him. If he is a member of net54, perhaps you can add an audit trail of the trade on the BST. There have been cases of trades gone very bad before, so you have to be cautious:
Link. I would say that since he initiated the trade request, perhaps you should say that you need to receive his cards first (which need to have tracking) before you send your cards out.