A rooster can be a difficult animal to paint because the finished product may appear somewhat absurd, as if it has been painted incorrectly. This is because roosters are generally odd looking animals, and uniformity of appearance between two different specimens is somewhat rare. Maintaining confidence in your abilities and careful study of your subject should take some of the challenge out of the task.
Begin by selecting a subject. Roosters come in different colors and varieties. Although you may wish to draw studies of a rooster to get a sense of its movements and musculature, you will most likely wish to paint from a photograph since you will be unable to make a real rooster sit still.
Set up your materials. You should paint in an area where you are comfortable and where you can easily concentrate.
Draw the body of the rooster and its surroundings on your canvas. Do not draw anything in great detail.
Apply paint to the canvas in a thin wash. Begin with the background and then paint the body of the rooster over it. When painting the body of the rooster, a medium-sized rounded brush will be best for applying quick, light strokes to the canvas for the feathers. When painting the legs, use a smaller detail brush.
Begin to build up the paint in thicker strokes. Notice that the feathers will fall on the rooster in a semi-orderly fashion, lined up in quasi-rows that contour the rooster's body. The strokes for the feathers should run along the body of the rooster as the feathers do. The tail feathers should have a flourish. Take care with the tail that the individual feathers appear singly.
With a fine detail brush, add the details around the eyes and the scales of the legs. If there are spots on some feathers, add the spots. You may want to add the line down the middle of some feathers to show the shaft. The amount of detail that you add will depend in part on your commitment to realism and the rest of the detail in the painting. You will likely not wish to make the rooster exceptionally more or less detailed than the objects around it.
Add shadows to the rooster's body to build up the sense of form and shape. Highlights should be added to the parts in direct sunlight.