There are a few differences between regular watercolours and watercolour pencils. While both the paints and the pencils give the art a soft wash of colour, the pencils will allow you to have a little more control when varying the intensity of the colour and blending it. You will be able to keep the lines a little more distinguished than you would with the paints. Moreover, the lines can still look like pencil if you so choose.
Lightly sketch your animal on your watercolour paper. Mark where you want shadows to go. Use a few jagged lines to indicate the dark shadows. Use light swirl marks for lighter shadows. (You will be using a lighter-shade watercolour pencil, or a lighter wash of your initial colour.)
Block in the background if you wish, and indicate where you want trees or any other landscape elements to go. Watercolours are great to use for backgrounds and natural elements due to the fact that you can work with them quickly . You can wash in a light-blue sky, dab in some tree leaves and bock in other plants or bodies of water all in a matter of minutes. Just keep the background colours light in order to enhance your animal, as it stays the focus of the foreground.
Use watercolour pencils like you are building something. Start with the foundation. Using medium pressure, colour in your animal's body with the foundation colour. Do not focus too much on filling in the white space; just pencil in a thin layer of lines for now.
Dip your brush into a little water and spread the foundation colour slowly and gently to cover your animal completely in a wash. Meanwhile, you will be doing the same to other areas of the composition while waiting for the base colour to dry a little.
Build up the colour with a little more intensity. Go back over your base colour with a few stokes of your pencil, and just deepen the colour in a few areas to add dimension to your art work. You can choose to use the moisture from before or you can add a tiny bit of water to your brush and deepen the colour that way. Keep in mind that the more water you use, the more the colour will dilute.
Use the paper towel to blot the water up if you are finding you may have used too much, or you are happy with the colour you have chosen. Blend a little black or grey into your base colour to deepen the colour and add shadows. You can also mix a few pencil colours together before adding the water. Try the blades of grass, for instance; use dark, medium and light greens with a touch of yellow. Block in the colours randomly, then use the small pointed brush to paint the actual blades of grass into the colour.
Finish your animal with details--such as eyes, whiskers and noses- with the black pencil. Use a tiny bit of water just for distinction. You do not have to use any water at all for tiny details such as the pupil in the eyes or stripes that may get messed up with water.
Keep in mind that you can always go back and draw over what you have done with the water. Just blot and try again. Try not to use too much water, which will wash your picture out.