I like the colour choices, they're very complimentary on the pallet but also different enough to be striking. Thumbs up.
I have two critiques:
The yellow could do with more depth, add some orange-yellow or yellow-brown to the areas that would be in shade and lighten the areas that would be in light with a little yellow/bone mix. The yellow is the colour that's detracting the most from the piece, it's a little too flat and too vibrant so it's drowning out the painting on the plates. That is unfortunate because the plate painting is where the party is at on this model and you want the eye to be drawn to that blue/green combination, not the edging.
Secondly I feel the base has too much grass on it, perhaps in the future you could go for a more sand look with a few patches of grass instead. I do however like the dead grass flock you've chosen, that's perfect for the setting.
Prior to painting the yellow it looked very flat. When I started to add the yellow it seemed to come alive and I got excited and I think I stopped thinking about shade and highlights! You're very right, though, toning the yellow would have been a better way to go.
In regards to the grass, I was of the opinion that tufts would break up the grass. In future would adding a lot more tufts also help with breaking up the grass or should I always go for a second medium like sand or dirt?
Thank you for your feedback. I greatly appreciate it. I've seen minis you've painted and have been impressed by them.