Part of it is breaking things into parts. don't try a whole character at once practice eyes, nose, mouth, until you master the elements. proportions are one of the biggest parts of any character. look through lots of images your brain will tell you what looks right. also you may have an image in your head but feel you cant draw it. Well its like any physical activity or sport. You have to build the muscle memory, your hand is going to fight you at first. kinda like learning to walk your legs make no sense then you get the feel for it.