Hello, my name is Aurélie and I started painting miniatures nearly five years ago. This is one of my greatest projects. This colour scheme for tyranids needs some time and patience, but it it's quite simple. All you need is an airbrush and Blu Tak for masking, so let's go! :)
1. First apply grey primer (Vallejo). The first layer is old Citadel paint "Vermin Brown" (it's an orange brown).
2. Then you start with the gradient at particular points (arms, legs, armor and on some organic areas like tentacles): first apply "Vulkan Green" (Forge World) for the green areas. Then mix some black into this dark green paint, this will create the darkest area of the gradient.
3. Glaze Waywatcher Green (Citadel) over the green areas (for a richer green and smooth gradient).
4. Organic parts/wings/tentacles: Step 1, apply "Flayed One Flesh" (Citadel), glaze with a mix of "Carroburg Crimson" (Citadel) and "Clear Angron Red" (Forge World, it's like Blood Red), then highlight carefully with "Flayed One Flesh" (Citadel). Apply the glaze carefully on a few select areas a second time. For the deepest areas you can use pure "Clear Angron Red". For the green gradient on tentacles follow step 1 to 3 again and finally step 7.
5. Mouth and the teeth: Mix "Ceramite White" (Citadel) with the old Citadel paint "Boltgun Metal" (any dark silver paint will do). Tongues: Create a red orange colour, I mixed old Citadel paint "Solar Macharius Orange" with "Wild Rider Red".
6. Only at the tips of the black parts, and grooves: Apply an wash of black oil paint diluted with white spirit.
7. Leave everything to dry overnight, then apply Gloss Varnish or Vallejo Still Water for an intense gloss effect.
Hope you like my Tyranids, tell me in the comments!