
try to avoid dark inside lines like those you can shade the object to match the shape good and show it good instead of doing dark inside lines like those to separate between objects clearly also if one of those dark inside lines you did was suppost to be shadow i recommend doing it less unnatural looking and more smooth like this for example

the point is the shadow that comes from the pink object to the blue object for this example i also marked it in yellow below so you can tell what im talking about