Most people here paint digitally, or (in rare cases) on glass, like the old matte painting masters. Oil paint is too messy, too fiddly, and dries to slowly for it to be useful for professional matte artists.
firstly try use good paints , they have stronger pigment(so you use less paint, tint less easilly, carry colour well, dont fade to fast, take longer when mixing colours to go brown and muddy, just have a richer feel.
i used/use winsor and newton griffen alkyd fast drying oils. stunning paint.
use a fast drying medium or dilute them with artist white spirits to lay out your first layers of colour on the canvas, much like blocking in, then once dry lay down heaviers layer and so on