You start with the head, more or less round.
Add the eye line, and then the torso and the neck to join it to the head.
As well as the eye line, the position of the ears and nose help to show which way the character is looking. Add the arms and legs, thinking about the joints and how they articulate. If you want to keep this simple and make the drawing easy to understand, you can leave out the (hidden) left arm completely.
Put in a few more details, you can get your character to put on whatever you like!
