Thanks everyone, I'll see what I can do regarding the colours. As for the texture on the "leaves" this is actually a type of cedar and doesn't really have leaves, so i wasn't sure how to define them like the pictures in the thread pistachio posted
Did you read the rest of the thread?
Even if it's supposed to be realistic, if the leaves are that small it's going to be tough reproducing them in pixel form then having them be recognized as leaves. Usually, like here, you get an ugly noisy texture. So having them be a little larger than they normally would be, for the sake of having them look like leaves, is alright. Post by JJ Naas further down the thread:
Doing realistic isometric pixel trees as game hart is a little bit difficult because first of all if they were meant to be really realistic, like this, then you wouldn't be albe to see individual leaves or almost any of the trunk (from a isometric perspective). However, using bonsai trees as a reference for game art purposes might be more helpful than using photos of real trees. With bonsai trees you get the cuteness, simpleness, individual leaves and often an isometric angle as well.
Even if your tree's not really isometric, it's still helpful considering you're still doing trees.
But the main reason I posted the thread is because you seem to be lighting up individual clusters of leaves, and not really focusing on the actual form as a whole.