First you paint all the canvas in yellow or other color...color are subjectives to our eyes it depends of who is watching...

after you can make your trees with blue because yellow and blue gives green, if you paint yellow to make green you paint the tree like you are hesitating on painting them, you pain the trees in stacato

after you meke the trees you make the lumber with brown and white or black and white as you wish

You see it's an easy way to pain just try it!