To drybrush this snake, you will need an old paintbrush with moderately soft bristles.
To give it a chalky look, do not wet the brush, if you do not want a chalky effect, wet your brush and then wipe it off a bit on a textured plate. You can do so on a paper towel too, but as paper towels absorb a lot of water, be careful to keep your brush slightly damp.
Take a bit of paint with your brush, and wipe it on a paper towel (for a chalky look) or on a textured plate (for a non chalky finish) until there is barely any paint coming off the brush.
Gently brush the snake with your brush, drybrushing is all about picking out the textures of the model. The direction in which the brush is going is very important for some effects!