I have been trying different underneath colors on my canvases lately. I am finding that I really like the effects of a pale warm orange (actually a combination of Cad Red Mid and Cad Yellow, and maybe a touch of White). I have been thinning this down quite a bit with mineral spirits so that it is a very transparent layer. I then have to let it dry for several days before using it. there are several reasons to do this kind of underpainting, for one, I really like the little areas where it peeks through and creates interest and a glow, as well as a warmth. It also tends to unify and harmonize the painting.
I am finding that this process is not always good for certain subjects. When painting a blue sky or white snow, for instance, it tends to bleed through after it dries, turning your colors toward pink or muddying them up. There are times that this can be an interesting brightness but many times it has to have a second coat to cover it. One thing I am going to try is an acrylic mix so that it will be thoroughly dry before painting with oils.
As a side note, these handy little stands were made by my handy husband and they work great!