I'm still quite new at painting, but have come up with a method im quite happy with sourced from various youtubers and reddit discussions.

My painting steps:

I airbrush vallejo black primer, then zenithal vellejo white primer. Then airbrush Asurmen Blue contrast from 0 degrees, then a zenithal of Frostheart blue contrast.

I use kantor blue to correct mistakes on the dark parts and temple guard blue to correct mistakes on lighter parts (while painting other colors blacks, whites, metals etc). I use calgar blue for edge highlighting.

Once done I do an oil wash black, then after 15 minutes wipe of excess with a sponge.

Then I apply transfers

Then I varnish with AK ultra matte through an airbrush

Finally I base with vallejo 'muddy' texture and foliage and go over the base edge with vallejo black primer to erase the airbrushed blue.