First you need to know the basics before you move on to choosing a faux finish. Imagine a tree with basic painting representing the roots and the trunk of a tree. Faux finishes represent two branches of that tree: positive and negative techniques. The faux finishes are the decorative tree leaves that everyone sees. Under it all the trunk holds the tree together. The root system or the preparation is what keeps the tree stable.
The color, style, furniture, and general design elements of a room will guide you in choosing your effect. You must have a clear plan to be successful. Control is the knowledge you have to produce the finish as well as the tools used to produce that effect.
A sponge, hair clips, brushes, or bubble wrap are examples of things that help you control the medium of the paint. The right tool means that things with handles, things made of plastic, and things that leave an impression are the most suitable. A tool with a handle will distance you from the surface you are working on. You can see the faux finish emerge clearly and you have the benefit of keeping yourself from becoming covered with glaze. Plastic is the easiest material to clean. Things that leave an impression offer a variety of finishes that highlight and shadow and create an optical illusion of depth. A large room requires a larger imprint and it also helps to speed up the time it takes to complete your project. If a large tool is used in a small room the effect can sometimes become overwhelming. Choose a tool proportionate to the space available.
Preparation of the item is the first step in creating a faux finish. This may require a sealer or just a good washing. Make sure you allow it to dry thoroughly before you paint the base coat. Allow the base coat to dry completely. Now is the creative part. Applying the glaze and creating your finish. Glazes modify the color of a base coat by allowing it to peek through. This creates visual depth of highlight and shadow. Always mix twice as much glaze with the paint as you think you will need. If you run out of glaze it is almost impossible to match the paint color.
Work from the bottom up, randomly applying the glaze. Avoid creating row, columns or any sort of structure.
If you are working with a partner remember that each person has different pressure and techniques when using the tool for the faux finish. Even though you may be working side by side the pattern will look different.
Be patient with yourself. The more practice you have the better you will get. Begin in a room or with a wall that is not the first thing you see when you walk in. Understand that you will make mistakes during your project. Some of the best finishes have been the result of mistakes. Have no fear in taking risks. Your greatest successes arise when you turn yourself over to possibilities.