As a collector of a Necron army I appreciate the work here and it is also your first mini which is actually very good.
I think that you could highlight the cloak a bit further just to give a good contrast to the metallic of the Necron.
You may want to try to add fine black lining to the separations in the various joints of the Necron as well.
All in all for a first mini it is very good you have some talent so keep it up and it will improve.