Jeremiah, beware of substituting "formula" painting for reality. An example of this is the way decorative artists paint their "formula" flowers...they have their place but are not realistic and all tend to look the same (see below). I highly recommend that you learn from reality first and then you can make up your own individual formula when you wish to shortcut and "fake it."
Mike, thanks for cleaning the black spots off my drapery. Wisk and Photoshop is an unbeatable combo.