Learn how to blend colors, also you could thin your paints bit more for less glossy finish. Work on your contrast, on his belt you can see some tools but don't know what it is. Its similar with his shirt and skin, you could blackline and make shirt in opposite colour than skin so it would pop out. Work on that and paint more you are on good way to be good painter. Good luck mate and have fun painting. Don't worry on weaker scores, let them motivate you to improve.