I think Icequeen hit the mark.
If you are thinking to enhance your natural gifts, then you should take into account the shape and features of your face, the relative size of your head compared to your shoulders, the length of your neck. It would probably be wise to go in for a professional consultation BEFORE you make a decision to drastically change your hairstyle.
If you are just wanting a change, I would still recommend some consideration before cutting off two year's worth of growth or so.
If you just want relief from the heat, then like Schleeed said, go with simplicity - just ditch it. (I know I'm not a very pretty girl, but I regretted going from below the shoulder to above the ear in one afternoon)
I agree with 'drew and parts, mostly, though ... it's your decision to make!
G.I. Jane, anyone?