watcha trystan first things first the NMM your doing is not bad dont get despondent it just takes time.
couple of quick observations not to be the big man just to try to help ok?
More contrast like black.....dark grey.....grey.....light grey.....very light grey.............tiny and I mean tiny dots of white on the sharp edges and heres the real clincher black right next to the white glints and edges so you have proper stark contrast. As 10 ball said to me think jewels. PM me I'll send you something got a mag or what not somewhere which is useful if you like. (er a painting mag before anyone comes out with cheeky comments I can hear you at the back Dragonsreach!)
Oh yeah do you use a flow aid or retarder in your paint mix? And do you thin thin thin the paints? Do you make sure to have two pots of water one to clean the brush and another one for a second thorough rinse and for mixing in your nice clean paints? Little things I know but at the level your at the little things are all that are left to improve.
Hope thats helpful and ive not come across as a know it all twat