These are my 15mm New Israelis and Xenomorphs from Ground Zero Games, which I painted up for a 15mm sci-fi "dungeon crawl" style game.
The New Israelis' full body armor suits were painted with a 1:1 mix of Vallejo Caiman Green and Khaki. Their weapons and equipment were painted with a 1:1 mix of Vallejo Black and Cold Grey.
The armor and weapons were washed with a 1:4:8 mix of Vallejo Black, water, and Future Floor Finish for shading. The high points on the armor were then touched up again with the Caiman Green/Khaki mix after the wash dried, the visors were painted with Vallejo Glorious Gold, and the bases were done in the same 1:1 Black/Cold Grey mix. I then applied some PVA glue to the bases, and sprinkled on some black sand. The whole thing was then sealed with a coat of Future Floor Finish, and then I used Vallejo Matte Varnish on the armor and weapons. The visors were left unvarnished so they would remain shiny.
The Xenomorphs and egg clusters were simply painted in a 1:1 mix of Vallejo Black and Cold Grey, washed with the same Black/water/Future mix, and then drybrushed with the black/grey base color again. Basing was done the same way as the New Israeli figures, and then sealed with a coat of Future Floor Finish.
I left the Xenomorphs in the glossy Future clearcoat because I liked the way the gloss lends a nice specular highlight to all the minute detail on them. The egg clusters got a coat of Matte Varnish because they looked a bit funny in the glossy clear coat.
The facehuggers were basecoated with Vallejo Earth and washed in the same way as the other figures, highlighted with a few progressively lighter mixes of Earth and Bone White, then sealed with Future Floor Finish and a layer of Matte Varnish.