Great looking dwarves, I like the shield design a lot. Almost look like a load of hammers. Sort of a dwarf version or ermine.
I would take inspiration from the heraldry books but these are fantasy races so don't get stuck on the rules as such. Also you can take inspiration from Viking/Anglo Saxon, Celtic, etc.
The simplest form is halving the shield, then quarters, perhaps a diagonal break across it, for dwarves geometric mountain shapes are always good, hammers are relatively simple shapes to try as well. Keep doing it and you'll get better. I find the best way is to paint in a dilute grey what you want to draw then go back over it with the colour you want.