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Learn to draw in black and white well before adding color. If you dont understand value, understanding color is hopeless, and will just cover up the basic errors.
Its a dead horse around here, im tired certainly of saying it, but you should do some life drawing each day, still lifes from stuff around your room will work. Its boring but its how you improve. It trains the eye, and lets you concentrate on value, light, and most importantly composition. Draw quickly, with cheap materials, from the shoulder. Do this a little each day for several months. Then start drawing a figure most of the time again. From life if possible, at least a mirror.
In general, you study how light works, how you see light, what light and shadow look like. Not ovals and boxes. Once you get this after a few months then consider studying anatomy, but remember you have a body, you dont need a book as much as you think you do.
If you need a book to study, get drawing on the right side of the brain for the exercises.