Im not the best person to be giving advice since I haven't actually mastered doing it in practice But basically you need to first find what areas have shadow both cast shadows and shadows that come from the object being curved To indicate the curve aka form you draw shorter lines that follow the contor lines of whatever you're drawing Important note is to aways pick the contour lines that fill the shadows using the shortest distance We can think of the tail for exsample like a cylinder and follow the contour lines that match the circle faces that make up the cylinder instead of the straight(in this case theyd be s shaped ish) lines that go down the length of the tail I definitely drew some of those form indicating lines wrong tho since I don't typically do line art so don't one to one copy the example Can kinda think of it like a slinky when you bend those around | Artwod Feedback