Here's some information about my process and materials. I'm using the Schminke Norma range of oil paints almost exclusively at the moment and have been for about three years. Schminke is a German company with a great reputation and is praised by professional artists around the world.
I stretch my own linen canvases. I find the surface texture, durability and strength of linen to be far better than cotton canvas. They are sized with rabbit skin glue size and primed with Schminke primer, which is like a half chalk ground. Four coats of primer gives a lovely surface on which to paint. It has just the right balance of absorbency and luminosity.
This is a linen canvas which has just been stretched on a pine stretcher and then sized with rabbit skin glue. The glue size tightens the linen onto the frame by shortening it's fibres. It is a traditional size for painting on canvas or board and prevents any linseed oil in the paint from getting into contact with the linen fibres. Linseed oil over time would gradually rot the linen if there was no barrier between them.
After sizing, I then prime the linen with four coats of specialist primer. This gives a luminous white ground. Oil paints have transparency which varies depending on the pigment used each colour. So in light areas of painting the luminosity of the ground shows through the paint layers to some extent. In the photo below the weave of the linen can be seen. I like the unevenness and slight irregularity of linen compared to cotton canvas.
Here is the back of a large linen stretched on a hand made cedar frame. Cedar is an excellent choice of wood for large paintings as it is very light and very stable, so it's warping is minimal. It also has a lovely smell.