Love this simple way to do palette knife trees in watercolours. Beginners will too!
Dampen the paper where the trunk will be, then just glide the knife into the dampness.
Change knives to add a different colour into the trunk, let it run a bit and use a finger to smudge and merge the colours a little bit.
I used a limited palette: Daniel Smith Quinacridone Sienna, Cobalt Teal, Winsor Lemon. Simple and fun.