Drawing is one of four essential elements of a good representational painting (if you’re doing abstract work, the drawing is not quite so important).
(The other elements are value, edges and colour)
In his book Alla Prima – Everything I Know About Painting, Richard Schmid describes drawing, in the context of a painting, as “the size, shape, and arrangement of all the patches of colour that collectively constitute a painting.”
Essentially, it’s making sure every patch of paint is in the right place and is the right size.
I often start a painting by sketching in the shapes of the main elements, as you can see in these examples:
It’s not essential to get this kind of sketch 100% accurate, as you can adjust things as you paint, but it certainly helps to get as close as possible to begin with, and if you’re too far off it will be impossible to achieve a realistic looking painting.
If you struggle with drawing, I can strongly recommend the book Drawing on the Right Side of the Brain by Betty Edwards. It teaches you to learn how to see like an artist, which is a first essential step to learning to draw. It’s also full of practical exercises to hone your skills.
One thing I’ve always found useful for keeping my drawing skills sharp is going to life drawing sessions. Accurately depicting the human form can be tricky, and it’s great practice for drawing, even if you only ever paint landscapes. I’d encourage you to try going to a life drawing class if you’ve never been.
Here’s a few of my favourite sketches from previous life drawing sessions: