The act of painting nude figures is a great tradition in fine art. Nudes are painted as a celebration of the masterful design of the human body. Common poses for subjects in these paintings include reclining poses, seated poses and even standing poses. Often in this type of painting, the subject is seen doing something a little out of the ordinary, given the lack of clothing. For example, the subject may be seen reading a book, staring into space or thoughtfully contemplating.
Pose your subject. The arms should be down and there should be no extremities raised above the heart. Keep in mind that a sitting or reclining pose can be tolerated for longer than a standing pose, and more complicated poses will tire your subject more quickly.
Draw the nude lightly on the watercolour paper. This drawing need not be involved or detailed: an outline and a very general indication of features should suffice.
Create flesh-tone paint with your watercolour. For lighter coloured skin, use reds, pinks, yellows and oranges, with perhaps a touch of blue or green. For darker skin, combine browns, oranges, reds and yellows with a slightly higher concentration of blues. The paints should be mixed on the palette. Dilute the paint for a lighter colour. Concentrated paints create a darker colour. Most watercolour paintings should start off with light layers which are built upon as the painting progresses. Remember, once a layer has been applied to the paper, it cannot be removed.
Test the flesh tone on a piece of scratch paper to see if your flesh tone matches your subject. Make adjustments when necessary and keep testing the paint until you're satisfied.
Paint a light layer of flesh tone on the subject on the paper. Don't worry about details or shadows yet--simply cover the body in a wash of flesh-coloured paint. Paint a light layer of colour on the hair, as well.
Build up the layers of the painting slowly by adding more colour to areas that need a darker, more concentrated flesh tone. For shadows, you will need to add more blue or brown to the flesh tone. Avoid using black for shadows--this will give an overall muddy appearance to your painting.
Switch to a small brush. Paint the features of the face, starting wherever you are comfortable. Less is more in watercolour; try not to address every line of the face. Instead, try to get the general gist of the face (a line for the top lid of each eye, a circle for the irises, a line for each eyebrow, a shadow on the side of the nose and under the nose, a dash of colour over the lips).
If this is your first time painting with watercolours, and if you've never done figure studies before, sign up for a life drawing class, or practice drawing figures before diving into this type of painting. Nudes are not the most complicated subjects to paint, but they're not easy, and preparing for the experience of painting a nude is especially important if you're painting from a live subject. You don't want to waste your subject's time, or your time. Watercolours naturally require the artist to be relaxed about the results of the painting, because controlling watercolours can be difficult, and often the finished product looks very different once it dries. You may wish to take your relaxed attitude to another level: try painting the nude figure in expressive colours (rather than naturalistic colours) and distorting the figure. Elongate arms and legs, exaggerate features as desired. If you wish to try to control the results of the watercolour, you may wish to let each layer of paint dry before applying the next layer. In this case, working from a live model is unrealistic. Work from photographs instead.