Today we started another painting.  Gesso the canvas to protect the canvas from the oil paints. Oil paints are very acidic so the paints will mess with your painting over time without the gesso. Now you can use an acrylic gesso for oil paintings but oil paint will definitely adhere better to an oil gesso. I typically paint on white surfaces but this can be a bit of a challenge because white is a very extreme color and same goes for black. Colors are all relative, in other words colors look different based on the colors around them. When you paint on a white or black background you may not be able to accurately judge the colors you lay down. A solution for this is to tone your canvas to some neutral, less harsh color. Seeing as this video talks slightly about gesso let me give you a tip with gesso and toned canvases. You can tint your gesso, all you have to do is mix the color you want to the gesso to tint it. I find most people like to tone the canvas after the gesso is done, they don't mix it because their really isn't a need to unless you're crunching for time. 

Example of a toned canvas 

This piece of art is by Teresa Oaxaca