Well fwiw here's my solution:
This was used on some 20mm Britannia miniatures so colours might need adjusting for bigger or smaller miniatures or your preference!
Undercoat figures with GW 'Dheneb stone'.
Ink wash whole figure with GW Devlan mud ink to shade uniform.
Paint 50% of visible uniform with thinned Vallejo US Dark Green.
Add occasional patches of pale sand to uniform - I used GW Bleached Bone for this.
When painting the camouflage colours onto the base colour remember to break colours/patterns at seams and pockets etc. This small detail hugely improves the look of painted camouflage.
The webbing and 'camel-backs' were left in the basic Dheneb Stone/Devlan Mud colour.
The bulletproof vests were painted with Vallejo Iraqi Sand then inked with GW Gryphon sepia to bring up the details.
The boots are painted with Vallejo British Uniform then given a heavy dry-brush with GW Terminatus Stone, which was also applied liberally to helmet covers, knees and lower legs of trousers.
The guns and goggles are painted with Vallejo Black grey.
The goggle straps, helmet strapping and chin straps are painted with Vallejo US Dark Green.
On 28mm miniatures it might've been necessary to add the darker 'black' flecks of pattern (using something like Vallejo black-grey) but the ink wash seemed to do that well enough on the Britannia 20mm models I was painting.