Here is how I approached painting the homebrew Space Marine chapter of @40_cake from Instagram.

Cool White Power Armour

1. Prime with Corax White .
2. Brush Corax White on to ensure you have a nice even basecoat over all of the armour.
3. Go over all of the recesses with a general recess shade of Fenrisian Grey . Thin the paint for all recess shading with water, down to a wash consistency.
4. Recess shade everything again with fine lines of Thunderhawk Blue .
5. Now take some Dark Reaper and shade only the deepest recesses.
6. Highlight all edges with a pure white, like White Scar or Vallejo Dead White . Keep the paint nice and thin.
7. On points and upward facing edges, do another fine edge highlight of pure white.
8. For the battle damage, I used small patches of dots with Dark Reaper and then a line of pure white dots of the underside.

Red Power Armour

1. Basecoat with Mephiston Red .
2. Recess shade with a 1:1 mix of Mephiston Red and Khorne Red . Keep the paint thin and make this quite a general shade.
3. Add some Abaddon Black to the paints from the last stage and recess shade again, with fine lines of this darkened mix.
4. Glaze areas that need to be brighter with Evil Sunz Scarlet .
5. Now add a chunky edge highlight of Wild Rider Red .
6. Go over all of the edges again, this time with fine lines of Squig Orange .
7. Selectively highlight corners and points with a 1:1 mix of Squig Orange and Ice Yellow .
8. Add dots of pure Ice Yellow to points.