It looks pretty good! Good colour choices. By painting skill, not something I'd do much better to be honest. But I am more critical than I am skillful (which can make it slightly demotivating to paint sometimes...).
And the main problem I see is: inconsistent (specular) highlights and lack of shading on some parts. And of course, neater is always better, but that's not very interesting to talk about.
Highlights are very important. Just as blends, they can make or break a model. So in general, you want to be really careful and thoughtful about placing them.
And no, even though everyone always seems to say it, it's not simply 'highlight the parts that stick out most'...and then upwards a little, as per 'zenithal lighting'. No, well at least not when you're doing sharp, bright highlights reflected off shiny surfaces (or slightly shiny).
It's okay for matte surfaces to highlight in that way, but then they also should be blended in more, since a sharply transitioned bright highlight like that simply doesn't happen on a matte surface, but of course you know that, so let's continue.
To make good specular highlights that work you have to consider what causes them and how the surface properties and lighting conditions can influence them. And they're very tricky to do right, since they emulate the direct reflection of the main lightsource (in most cases, the sun, you can also have multiple, it's even trickier, but looks very impressive if done well). Which is dependant on both the viewing angle of the surface and the angle of the light hitting it. So it's really entering NMM territory.
The lightsource you can easily just 'simulate', by have it being right above the mini (again, zenithal lighting). But the viewing angle is trickier and you kind of have to pick and choose optimal/average viewing angles of your mini and work from there.
You could go al technical about it and calculate/measure roughly for each point on your mini where light hits where the light has the same angle to the surface normal (which projects perpendiculary from the surface, think Pinhead, all the nails on his head are technically, well mostly, also the normals of the points they project from) as the viewing angle.
But that's a hell of a lot of work. An easier way is to either look at (photograph) the unpainted metal model with a light above it (in a diffuse or dark environment, no sun), or coat the model on key places with a shiny wash of paint (which you can then stip or paint over). This creates a great reference point on to where to put your hightlights. It's also a good learning experience, as highlights can appear on places you'd never expect.
And the lack of shading I pointed out is mostly the boots, compared to the rest of the model they seem a little flat.
Finally, more on the photography, I think a bright mini like this would look a lot better on a darker background.