Well my advice for almost anyone just starting out is just put something to paper. Distilled to a basic level a settlement map is boxes next to lines. You can change or revise or redo or fix an existing drawing more easily than you can a blank canvas. Once comfortable with making maps you can start looking into the intricacies of X regional historical town layouts, or how towns developed, or all that more complicated stuff later. It'll be easier to handle too 'cause you can just incorporate those ideas into your next map, which you're already comfortable drawing.