Keep your lighting scheme simple
There’s only one rule when it comes to 2D illustrations, and that’s to keep it simple. Actually, this is more difficult than you might think, because there’s always the temptation to add a few lights here and there to complement the details. Most of the time one key light placed either top right or left, and a fill light on its opposite side does the trick. Make sure that shadows aren’t casting over either the face or key elements of your model. Now you’re ready to render!