After the base color is set you have to make the dragon look more 3d than it actually is one way to do that is add shadows and add light. the way i do both of those things is by using the pen tool to overlay a solid black layer and then lower the opacity between 20-10 (depending on the color your shadowing.)
the large box above shows the eyes of the dragon which have more of a flare to then a solid stark color yellow i added variations of white and black to spherical it. the same can be seen in the second box the wing has a lowered opacity that will benefit once a background is behind it. but also some basic black and white figures in between the two to demonstrate depth.
step 4 will involve more details and textures along with color variation