Anything & everything can be derived from these three shapes.

Learning to draw is, learning to see, to draw WHAT YOU SEE, and not to DRAW WHAT YOU THINK YOU SEE. " The stem doesn't make it an apple." What us the 1st basic shape you see of your subject? Don't draw the subject, draw the shape. Is the height and width correct? If so, then break it down into smaller shapes within the subject, and so on. Your subject will appear all by itself. REMEMBER, stand back from your draw on a regular basis, check if it's correct before moving on to the next step.