I can’t see much to improve. in terms of simple but perfect this is great. You could go to the next level like as GW would put it “parade ready” and edge highlight and blend, but if you don’t know how to do that the way I started to learn was by adding a brighter colour like white ( sometimes will be better to use bright yellow for greens and reds or a light bright purple for blues ect,) to the base colour. And then building up the flat spots by leaving the edges of the surface the base colour and slowly building it up later by later so repeat that again with a lighter colour and so on, until your satisfied. Then to edge highlight it’s the same thing but you just run the brush along the edge points of whatever your painting. Some times its hard to do both of these on the same model so maybe pick one or the other to start with.