The Fundamentals of drawing are very simple, Anatomy and Perspective are certainly in top 5 most valuable skills for improving. Learn some Anatomy and draw better right, sounds simple but the reality is Anatomy alone takes years if not a lifetime to master, that's why it is important to start educating your self as soon as possible and as much as possible, going to your local library and checking out some of their art books is in some ways better then clicking through the endless internet
The Stereometric Method
The Stereometric Method was devised during the Sixteenth century in a period know as the Renaissance, Italian Mannerist painter Luca Cambiaso created many sketches and compositional studies with many levels of schematization. Painter Piero della Francesca, Paolo Uccello, Albrecht Durer, and Leonardo de Vinci all used this method before starting and big work.