don't wear too much, but most girls will find it attractive. no matter how masculine a girl may try to be, there is still a little something deep inside her that likes a little feminine in her man ;)
As long as its real gold or silver its nice. Just don't over do it. Have only one chain on, not too thick, not too thin and not too many rings either. Rings look good on guys if their worn on the pinky and 3rd finger.
It depends on the style that the girl likes. I personally don't like guys that wear jewelry or dress metro-sexual, but if that's your style don't change just for girls.