Use water-based/soluble mediums if possible.
Don’t get caught up in the detail. You are giving yourself a base to work from, not painting the whole picture.
Use water where you can. The lack of fumes is better for you and creates a work with less chemicals added.
If you use odourless solvent, please be aware that odourless is not vapourless and the fumes can be harmful. Use in a very well ventilated area.
Don’t lay down too much pastel before wetting it. You will fill up the tooth of the paper, making it difficult to add layers of dry pastel over the top.
You don’t need to paint the whole picture. Often you can get away with just underpainting one or two areas.
Keep your brush clean. Rinse between areas of different colour, unless you are wanting to merge colours.
Use an old or cheap paintbrush as sanded pastel paper eats paintbrushes.
Re-seal any leftover solvent, or allow it to evaporate outdoors.