These are a few methods of camouflaging with spraypaint. Remember not to spray to much, as this will cause runs and blemishes. It is a good idea to practice aiming on some card board or something before you start.
There are many deviations of the methods I will give, but they all follow the same concept of how they are done. Camo essentially consists of layers of colors in different patterns. in this case, each layer is applied using masks or stencils to create patterns.
It is also important to make sure paint doesn't get anywhere that could damage the gun. Use painters tape or masking tape to cover these parts if they cannot be removed. You should tape orange tips, joints, and holes that lead to the inside of the gun.
Step 1: Stencils
The method of using stencils involves putting something on the surface to keep paint off certain sections then spraying the entire surface with one color. They are not removed after each coat of paint. The colors will appear to be stacked in the order of application(eg. first color on top to last color on bottom)It is important to apply the stencils so that they are flush with the surface so that they do not let in any paint. Stencils can be applied either by spraying the back with some kind of adhesive or using tape.