Get ND Grad 4.
People say it for landscape only? Nope.
It is basically if you have unbalanced brightness & extremely contrast subject where bright is over-exposed, so it is difficult to meter.
Do remember, get the GRADUAL filter, flat one is normally of no use now with digital camera
Sample with ND Grad filter (#4) - taken from Anime Festival Asia 2008 - this figure of Saber (from Fate/Stay Night) in French Maid costume was under a spotlight - with her blonde hair for sure cause overexposure, and if you correctly expose her head (face & hair) you will not get the body cos it is dark blue. I took his with Cokin ND4 grad + polariser to reduce glare, and I still have to set EV-2.
I also flash so I get some detail from the costume.
Some part of the hand and the hair is still overexposed but I can live with that. This I took on 2nd day coming prepared.
Later using post processing I bring up the brightness of the shadow area a bit more and reduce a bit from bright area, and this is the result.
Below pics I took on 1st day coming unprepared.
Without ND Grad filter (best attempt). OK white balance a bit out but I cannot make it that better without resorting to spend hours with multi layer etc. You cannot see the legs after correctly exposing the face.
Without ND Grad filter (feel the burn). This is the worst. Granted it is a bit blur due to hand shake but you can see how the detail is lost due to overexposure of the hair. I am trying to correctly expose the face.