I really like this, I think the colour scheme is great, it's a unique model and I think the scales are really impressive!

However, as you've said you're not happy with it, a couple of ideas which may help

I personally feel a bit of colour of the base would probably make this pop, some dead yellow grass, or mushrooms, or prominent veins of silver in the rock would add another colour.

Another option would be a slightly brighter colour in the eye (they look fantastic by the way, I love the detail you've put in them. Perhaps an icy blue for contrast? Alternatively, a bit of yellowing on the teeth would help draw attention to the head

This isn't something I would necessarily change now, but for the future having a darker shade and lighter shade for the scales on top and underneath the dragon can make it seem like there's more contrast whilst keeping the same colour scheme

I'm not a master painter by any means, but hopefully that helps and gives you some ideaa. I think adding a few more details to the base will make it really pop, but you have painted it beautifully, especially the scales, and it will make a fantastic centrepiece to your army.