Good work so far !
First off you are definitely brave endeavoring on a white heavy army. They do look amazing and are some of the trickiest to do well, however you are well on your way.
My only suggestions is perhaps to thin out the white a little more using either water or mediums ( Such as Lahmian medium produced by games workshop, or Flow mediums produced by
Jo Sonja's ). This will require some trial and error to find the right consistency ( which using a dropper/needleless syringe could help to measure if you don't want to wing it ) and will need multiple layers, however the end result is smoooooooth
I would recommend highlights on the green parts ( As stated above ) using just 1 or 2 shades lighter then the base layer used, and also considering highlights on the Brass parts. I find that certain silvery paints actually act amazingly for gold/brass areas.
As an example, Games Workshop produce a colour called Liberator Gold. If you haven't seen it before, its a fantastic mix between gold and silver and works amazingly to highlight gold with and could even work when mixed in with the brass colour you used.
As stated above, I agree with the battle damage. While this is a personal preference , I find battle damaged armies have such character to them. There are many ways to easily and effectively represent battle damage using only 2 different silvers and a brown wash ( to add dirt ). My favourite method to represent gunshot ricochet's off armour is to paint a tear drop using a dark silver ( with the large end toward the front of the model, aka the point of impact) trailing to the tail away.
Then, replicate this tear drop using a lighter silver staying WITHIN the darker silver tear drop, and it gives the illusion of a scratch with varying depths.
For extra points, use the brown wash and a fine detail brush to drag very find streaks down from it to represent dirty water / rust streaks .
Yeah, I could go on forever...
Great work man keep it up !