Re-draw the outlines in pen and shade in the pair of them. Mark out the stripes or any other patterns along their bodies.
Colour in however you like, though common lizards are usually brown and grass snakes are green and yellow.
Use a pen to go over the pencil markings. I created scales to the side of the body with a series of light circular motioned scribbles.
Lastly, I coloured the adder in. Red for the eye, a blend of yellow and brown for the body and yellows, browns and greens for the leaf litter. I went over the leaf litter with a pen and added the forked tongue for the snake.
And that concludes my session on reptiles. I hope you will go out and find some for yourselves. They are beautiful creatures and are great subjects to draw. If your afraid of snakes, have a go at drawing them and hopefully, you will find that they are nothing to be scared of.