Most of my paintings are on canvas or wooden panel, although a few have recently moved onto aluminium. Whatever support I use a solid backing is preferable. So canvas is stretched over wooden panels and then either kept like this or re-stretched when finished over traditional stretchers. This removes the bounce that you get when working on traditionally stretched canvas which I have never been the greatest fan of.
The surface preparation involves many layers of acrylic primer, all layer finely sanded until eventually the canvas weave is lost and a smooth surface left. This is partly why there has been a progression to an aluminium support where the surface is already smooth and needs far less priming and perhaps a more stable surface in the long term.
More recently the final priming surface has been using an oil based primer giving a more fluid initial surface to work on than the more absorbent acrylic. The colour of the ground is then considered. It can either be used straight off with the white primer as a base colour or it is then either coloured with a warm ground or a cooler ground.This can be applied either as a wash layer or as a much more solid colour.