Sorry that you had to withdraw, and hope that everything is OK.
In regard to the mini there are several things I think you need to address.
Firstly there are a number of \"Blank\" patches on the mini, The legs, the waist and the left arm holding the shield. As someone who\'s been in the fortunate position of judging minis I can say with confidence that they would be \"eye catching\" and detract from the mini.
Also as Trevor has suggested NMM doesn\'t always go down too well in GW competitons, but when it does, it does need the extra \'eye candy\' of good contrast and (for want of a better description) light modelling, where the Light and Tonal regression from the \"Flare\" are smoothly defined into shaded areas.
On the Waist skulls I have to agree that the use of GW Charadon Granite would be a good starting point as would GW\'s Deneb Stone. (Both Foundation Paints) From either of those starting points you could easily add tiny amounts of Bleached Bone (I prefer Vallejo Ivory) to raise the highlight levels. In addition thin glazes of GW\'s Graveyard Earth can add a touch of subtle shading around the Skull Temple indentations and teeth.
On the face, which needs to be the focus of a mini the, painting and attention should be really precise using careful changes into the highlights and really gradual shadow transitions.
Lastly and one of my own downfalls is the base. For competition mini\'s the base is as important as the rest of the figure and needs to be considered as an integral a part of the mini as, for example, the cloak. My biggest fault with bases is to not give them enough depth of shading and contrast. In that I\'m not suggesting wash over with Black but think about tones of dark brown (Vallejo German Camo Black Brown) as the shade in the crevices.
I hope that this lot helps and you have better fortune in the next GD.