TalentThis is where it all begins, isn't it?
Singing VoiceAh, yes--I do love a guy who can sing. When it comes to male vocalists, I seem to favor tenors (particularly clear, soaring ones) but I'm really not picky about exact range; it's the skill level and the ability to pack emotion into a vocal that makes me sit up and take notice.
HairCall me strange if you like, but this is indeed one of the things I tend to notice most. I'm not fussy about color, so long as it looks at least marginally natural--I draw the line at pink, purple, etc.--though very blond or very dark seem to hold the most appeal. I am also a definite child of the 80's in that I adore long hair on a guy. (The better to thread one's fingers through, perhaps? 
) Short can be acceptable, however, if it's clean and properly cared for; the "I lost my comb two weeks ago" look of grunge doesn't do it for me.
EyesAs with hair, I'm not too particular about color--though again, I seem to favor either very blue or very dark. What really gets me, though, is the life behind the eyes; some men seem to be able to see right through you, or their gaze sparkles with merriment or smolders with some barely contained inner fire, and that's the kind of thing which really reaches out and grabs my attention.
BuildI think most women appreciate a well-put-together fella, and I am no exception. A good upper body--broad shoulders, muscular chest and arms--is especially attention-getting.
HeartAny good musician's got to have a heart--that's where the best songs come from, after all. And while I'm well aware that the world of the rock star is largely one of smoke and mirrors and only marginally related to daily reality, knowing that a guy is pretty nice in real life as well as onstage can only increase his appeal...
ClothingOnce again, I am a definite child of the 80's here. The fashion world may have long since moved on, but I will probably always love the "look" that was popular back then. And especially the varations which had a touch of the medieval or fantastic--witness my liking for leather pants. 
(Pair them with a ruffled shirt, and I'm ready to swoon on the spot!)
InstrumentOptional, but nice. Let's be honest, here: Someone who has enough manual dexterity to play a musical instrument is probably good with his hands in other ways too, no?
AccentNot truly necessary, but a definite plus if it happens to be there! It's great when a guy who can sing has a nice speaking voice, too, and an accent is the icing on the cake. Just about any kind of a foreign lilt is lovely (British/Aussie, Dutch, Swedish, etc.) and I've, erm, recently developed something of a liking for Southern drawls, too... 
EarringA nice, if optional accessory. There's just something about a guy with an earring...
