I want to help all the beginning artists that come here looking for help improving, but as I don't often find the time to give them the kind of help they need I'm putting some basic lessons here for everyone to get.
I'm starting you all on basic exercises so they will seem boring, but their simplicity will serve you best in the long run as the form the foundation for later skills.
Contrast is what makes images pop, and while there a bunch of different kinds of contrast, the contrast of value (dark against light) is possibly the most important. So today let's focus on value and shading. For more general tips, look here.
I work mostly in traditional media myself so that's how these are written up. If you prefer to do these exercises digitally that's fine, but I want you to stick to greyscale. Color and saturation distract the mind from value, which is what you're trying to master here. Also, use only the brush tool- no burning, dodging, or blurring, as a dependence on these will only handicap you later. Get in the habit of working at 300 dpi, which is what you need if you ever want to print your work. Don't save as a jpeg except when getting ready to put it online, as jpegs are extremely lossy and the image will degrade.
Exercise 1- Value scales
You'll need
-a ruler
-drawing materials- Charcoal or pencil, drawing paper, and an eraser (white plastic or kneading). If charcoal, use vine or willow (not white or compressed).
Using a ruler, mark off ten one inch squares adjacent to each other.
Your goal here is to make an even scale from dark to light.
Shade the first square as dark as you can get it. Leave the last square blank.
This is a good example of what I want, except that the artist here has a bit too big a jump between the first and second shades and the midtones are all too close. I think you can do better. Make the values as evenly spaced as possible.
Exercise 2- Drawing a Sphere.
You'll need
-a sphere of some sort- I want you to look at a real object for this rather than just copying from one of these drawings, since part of what I want you to learn from this exercise is how to draw from observation.
A golf ball would probably best since it has so little surface texture to distract you, but I guess any sphere will do.
-drawing materials- Charcoal or pencil, drawing paper, and an eraser (white plastic or kneading). If charcoal, use vine or willow (not white or compressed).
You'll be focusing on lighting for this, so put the ball somewhere with a stable light source where you can see it easily and it won't be jostled.
Next, draw the sphere
I want you to draw the sphere and make careful note of all the lighting. Include the shadows cast by the spheres.
Check out the diagrams here and here
Look at the sphere and find out where the very darkest point is and where the very lightest point is, and make them your darkest darks (completely filled in pencil) and your lightest lights or highlights (the white of the page).
Reflected light from around the room will make some of the shadows lighter than you'd expect, mainly around the edges.
The cast shadow will be deeper the closer it is to the base of the object, but depending on the light source that may not be very noticable.
If you need more help figuring out how to do this there are some overly complicated instructions here, but I think you should be able to manage with just what i've given you and by looking at the sphere and the shadows and back at your paper.
These skills can then be applied very simply to more complex objects.
Good luck and happy arting! Feel free to post work in the thread here for feedback.