I've had a few requests on here and on Facebook to give an overview on how I paint my models, I generally follow this same process for everything just with different colours based on the effect I'm trying to reproduce. I tend to find myself using a mix of Vallejo Model Colour and Citadel Contrast paints. I like the more muted military colour range of Vallejo and the Contrasts are a very interesting alternative to washes and glazes.
I documented the process for these two BMP-1s both with a different colour pattern, inspired by photos found online.

To start I primed both models with Games Workshop's Zandri Dust spray, honestly any beige, khaki or grey colour will be fine just get a nice basecoat down to prevent any paint rubbing off.

Basecoat the lighter model with Vallejo Iraqi Sand (70.819.) Camo is left in primer since I want a darker base however I added patches of Russian Uniform WWII (V.M.C. 70.924) randomly across the hull.

Next is an all over wash of GW Skeleton Horde Contrast paint and Contrast Medium mixed 50.50. Camo gets the previous mix with a little Wyldwood Contrast added to darken it further. A nice diluted mixture that won't pool on the flat surfaces or leave tide marks, thinning with the medium is definitely recommended as water doesn't work near as well.

Both models were carefully pin washed with Wyldwood, be fairly careful here particularly on the larger panels but clustered areas of detail can get an all-over wash since they'll be fully highlighted later on anyway. I finished up the turrets at this stage to clarify I was happy with the result hence why they've jumped onward.
Before I start the highlights I also add a black wash to the track recess, I tend to use Black Templar Contrast with the deepest areas getting a little thinned black to darken them completely. Doing this now prevents any painful re-highlighting if the brush slips onto the wheels!

Next the panels are all picked out with Iraqi Sand, this is where being careful with the pin-washing stage pays off as it takes much less time to get everything looking neat. Camo gets the body colour done with Khaki (V.M.C. 70.988) and the patches cleaned up with Russian Uniform where required.

Finally I add a couple of edge highlights progressively lightening the Iraqi Sand with pure white. Camo gets the same progressive highlight process just with Khaki and Rus. Uniform mixed up with Beige (V.M.C. 70.917). Adding white tends to make greens too desaturated so a yellower white is needed.

The final near-white highlight is used very sparingly on the sharpest edges and details to really make everything pop.

All that's left to do now is finish off the details and paint the tracks (I like just black highlighted with grey for mine.)

And that's them finished! I tend to lightly varnish them with some matt varnish and add a little gloss to any vision ports or lights that I'd like to have some shine. The matt finish tends to dull out metallic paints so some gloss brings back the effect.

A pair of happy little BMPs.
Hope this is useful for some, it's obviously a serious undertaking to paint any sizable quantity this way but even for command vehicles or such it can be a nice upgrade. The high contrast finish makes the models clearly visible at table height and really takes advantage of all the wonderful detail on GHQs models.
Cheers
Chris