Here is part 1 of Do's and dont's when designing covers, etc.
If you have any questions, I will try my best to answer you!
This list is aimed specifically at editing models.
DO NOT:
Do not make highlights and contouring harsh. It may look messy and undefined.
::
DO:
Start softly and gradually buildup.
With highlights, try having a small yet concentrated area, instead of big area that has little definition. Adding some texture to highlights can be done using a glittery brush or overlay at a low opacity.
Learning about how and where highlight and shadows should be can take your graphics to the next level.
:::::::::::::::::::
DO NOT:
Don't forget to highlight and add shadows to the rest of the body too. Not doing this can make your graphic look odd and incomplete.
::
DO:
Do the necessary editing on the rest of the body too.
:::::::::::::::::::
DO NOT:
Don't forget to edit the hair on your models.
::
DO:
Use a smudge tool to smoothen out hair (and skin) and reduce grain.
Add highlights and shadows to hair as well.