Look around for a simple object that has some strong darks and some very light lights. An onion or an apple would do, as would a tea pot. Make a painting of the object. Keep it simple. Shape is more important than texture. It is not necessary to make sure the rest of us can tell what you were painting, but take all the time you want. Now paint it again. And again. Paint it at least 4 times. As you become more familiar with the subject you will naturally find some features that have to be right and others that can be approximate. When you start to feel that the brushes and the paint are behaving dependably, put the object away and paint one from memory.
Please send me your studies, especially the one done from memory. Label your work with your name, and keep the image files down to no more than 300 dpi per side