|You can get pastels at most art supply and hobby
store, even Walmart carries them. Do not get oil pastels. Oil pastels are
the most common type at an art store but they are not what you're looking
for for shading a model. Get the soft, chalk like ones. You don't need a
large set, black, grey and brown are the ones I use the most. If you have
a choice between a set of dark colors and light colors, get the
dark...you'll use those more. Also get a stiff paintbrush (I use a #4 flat
camel hair). Never use the paintbrush for anything except the
pastels...also never get the brush wet, that would be bad if you tried to
use a wet brush (it's like mud).
To shade a model, paint the main color, do some drybrushing too if you
like, then rub the brush onto the pastel stick a couple times to load it
with color dust and then scrub it into the paint. The color builds up
slowly so keep at it until you get the intensity you need. If you overdo
it, clean the brush by rubbing it with a paper towel until the color
doesn't rub off anymore, then scrub at the area and it will become
lighter. If you really need to clean an area off quickly, moisten a paper
towel (as in barely wet, not very wet) and rub it gently across the area,
the pastels will mostly come off.
When you've got the figure the way you want it, lightly mist the figure
with sealant. Don't spray the sealant directly onto the model or you might
a) blow away the dust; b) flood the dust and cause it to run; c) both a
& b. I use Dullcoat, pretty much just because it's what I'm using
these days to seal a model.