After participating in Kelley Berkey's drawing challenge I was asked to share some tips/hints on how I draw with charcoal. I figured there may be a few other people who would like to know a bit about my drawing process... I hope this information will help you in some way.
I go about drawing with pencil and charcoal in very similar ways. Above is an example of my pencil/graphite drawing and the drawing of Kelly done in charcoal can be seen HERE. I first start with a light sketch of my subject. I try to crop or angle to the most interesting view. I prefer to work from top to bottom especially when I use charcoal because it can smear quite easily. It helps to lay a clean sheet of paper under my hand if I'm working over something I have already drawn... I don't want a grungy looking mess to happen after all the hard work. Whether I use pencil or charcoal I never just use one pencil unless its a super quick sketch. If you aren't aware of the numbers and letters on the pencils, it is useful information. H means the pencil is hard and will show light lines, the higher the number is with a H the lighter it will be. B's are soft and give you darker colors... nice contrast to the H's. B's will give your picture depth. I use 6B to get my darkest areas in my drawings. When using graphite pencils I prefer working with the pencils from scale 4H to 6B. For charcoal I use HB, 2B, and 4B with a lot of blending and erasing to give an even larger scale of lights to darks.
For a realistic look, blending is key. I use pretty small pointed blending stumps... I've never had a need for the large ones. If I'm working with a large area, I use my finger. If I'm using charcoal and I want an area to look really black, I will not blend it. I simply work up the dark color in layers until it is solid and you don't see the paper any more. If you try blending it, it loses the rich dark color. I start with the lighter areas and gradually layer up with the dark areas/shadows.
Another useful tool that helps me immensely when drawing is a needed eraser. You only need a small one because you can keep pulling on it to have it clean its self. I like to roll it into a point and use it kind of like another pencil only it takes away to give lighter areas. This works awesome when working with charcoals and you want a smooth transition between light to dark or if you want to give highlights to an area.
I use my needed eraser and blending stump more often then I use my actual charcoal pencils. Sometimes when I'm wanting a light gray area, I will just use my blending stump. If there's already a bit of charcoal left on the tip I press softly with it to give light gray areas. I will then use the needed eraser to lighten any spots where there isn't a smooth transition.
How much time you spend on blending is entirely a personal preference. I like to layer up with a variety of pencils and then blend... sometimes it is harder to erase after you blend and of course the harder you press the harder it is to pick that color back up.
I suggest if you're new to drawing start with drawing a ball and play around with the light to dark ranges. Practice making it look and feel round. Make sure you think about the light source (where the sun or light shines on the object)... you will need a highlighted point (white area) somewhere with a shadow (your darkest area) that the light is not shining on. The contrast is what will make your image pop.
The more you practice the more you will get used to your pencils, blending stumps, and needed eraser. Have fun!