I guess a good place to start is to do some shading exercises, like shading spheres, cylinders, etc.; more so for you to get the hang of the materials that you'll be using. Pencil is really good for getting detail, but many beginning artists have a really hard time getting the shading to be really dark, whereas charcoal can get you those glorious shades, but is difficult to get great detail if you don't know what you're doing - pretty much why getting used to your tools and knowing how to use them is important to get a hang of before you start drawing the more complicated stuff.
Other than that, start practicing every day by drawing some life studies, of people, objects, etc. Always observe carefully what you see first and then start drawing. This is important because it trains your eye to draw what you see, rather than draw what you think you see.
There are many books (like the ones mentioned above) and classes out there that can teach the basics, which are great for teaching the right techniques rather than getting into bad habits (straw lines for instance). So while it isn't necessary to read books or take classes to learn how to draw, it will help you learn techniques that will help you learn faster.
Hope this helps.