Kids love to paint and play with colors. Just give them some colors to play with and you’ll see their creativity dabbled on the floors, on the walls, everywhere (well, of-course we don’t want to encourage them to do it on the walls).
The point is that children love colors. However, at times the paint brushes aren’t as much fun as finding other things to paint with (at times even adults get excited about this while thing when they do it with kids).
Other alternatives are your fingers (of course), comb, brush, cardboard, sponge or even an old toothbrush.
The best thing to do is to keep a box of such painting materials that can be used during your painting time with kids.
Unlike oil pastels (Camel, Faber Castel, etc.), Dry Pastels, also known as Soft Pastels, have a higher level of pigmentation resulting in brighter colors.
Want to be more creative? why not add soap powder, dish-washing liquid, flour, sugar and/or sand to the paint and we see what happens? Of-course your kids will use these under your supervision.
But the point is that these seem to make the painting activity even more interesting than just using different colors & the standard paintbrushes.