Don’t freak out if you think you can’t draw.
It’s alright if you’re accustomed to drawing stick figures… you’re one step away from being able to draw! It’s really rather simple after you get the gist of it. There’s no need to get special sketching pencils either, a mechanical pencil will do.
Start practicing by drawing small objects: for example, I will be drawing an eye. Focus on the shapes in your image. Whenever you sketch before you start a painting, don’t fret about getting every detail down pat. Just draw relative lines that will help guide your painting process. As long as you get the right proportions, you’ll be satisfied with the end product.

Proportion lines come in handy to guarantee a balanced drawing. To properly use proportion lines, use your pencil at arm’s length to simply measure one point of the image to another. For example, from one corner of the eye to the other corner.
It also helps to create these lines with sharpie or a pencil on your printed out image. This helps split up your image into shapes, and assures the correct distance among the drawing. It may look a little strange at first to see lines all over your drawing, but you will be painting over them.
After you’re satisfied with the drawing, it helps to shade in a few dark areas so you know what parts of the painting need value.
Now you’re ready to paint! And remember, practice as much as you can on paper before you start on canvas (to avoid disappointment and you’ll honestly be more comfortable with exercise).