well...
first of all practice a lot on layers' cutting and use magnetic lasso tool if you are using another tool (it's much more easier!)..
then,there are too much jaggy lines,you need to make them much more smoother using highlights,shadows etc..
I also can see many wrong perspectives,and many parts look too "boxy".
So,be careful with cutting thing,practice on your brushing to make it smoother and more beautiful and take your time on the perspective to make your chops' scheme look correct and nice
If you have difficulties,post on the wips' session to take advices from other choppers while you are working on something..
Something last,take more time on your chops,don't make them in hurry
keep up working
