Thanks for the info. I will check that.

What I was doing is that, after painting the model dark yellow, I added the brown and green camouflage. Then, with a cheap paintbrush, I just drybrushed my model with a little bit of dark yellow (same colour that I used at the beginning). Finally, I drybrushed my models with Vallejo Iraki Sand.

When do you suggest using the sponge brush? When I am applying the camouflage or after?