I am forever tempted to start up collecting and painting again whenever these threads pop up.

Man it's been such a long time since I played Warhammer!

Painting was probably by far my favourite thing about the hobby as well.

I don't mean to offend you or anything, but I think there's definitely room for improvement, but you certainly understand some of the minor details that make a huge difference to some people, myself included.

Do you use a base layer? If you don't then it's worth investing in some of the spray cans and given your models a base layer, it really enhances the colours and I think it helps give the end result a smoother look in general.
Some of the solid metal miniatures aren't as nice to deal with because you can't give different parts different base colours, but with the plastic models you should consider that if you really want to make them pop.

For light coloured models I always used a white undercoat and for darker coloured models I used black. Of course it's all trial and error and different colours work better than others and give different results, so it's up to you to play around with different colours and see the different results you can achieve and how much it can compliment a particular colour and model in general.

Another thing I loved to do with the mechanical models was to incorporate some sort of rusting or wear and tear, like a watered down copper paint and lightly apply it in certain areas to really add that extra level of detail. Same thing I used to do with Orcs in traditional Warhammer, I'd water down black paint and sometimes a brown paint to add a layer of grime and dirt, I personally thought it made them look how you would typically expect an Orc to look and was often complimented on it, and it's so simple to do! With the watered down black especially, it really hmm can't think of the right word, but it makes the lines of the muscles really stand out almost like shadowing, it's a real nice extra touch.

Anyway, I like your models but I thought I'd add my thoughts because I know when I was playing, painting and how they looked was really important and the most fun part, so I hope you like the ideas and maybe give them a try :)

Looking very nice I must say.

Keep up the good work.

Although I've always been an imperial guard man myself.

I am forever tempted to start up collecting and painting again whenever these threads pop up.