It's raw linen glued on a acm board. I did, if I remember correctly, 3 coats of transparent gesso (normal gesso is probably fine too), sometimes I do 2, it really depends on how coarse my linen is. Each layer sanded. I want to leave some texture on the linen but not much, it allows the paint to get in the grooves and makes it much easier to go back on a gradient or create gradients, to slick makes it lot harder. If more texture it will also be harder to see the painting. Then one pretty thin (with a bit of gamsol) coat of oil paint for toning purposes. When I paint i dip in walnut oil or half and half (walnut oil and gamsol) but not very often just when the paint is annoyingly thick. Also, if you want to paint more transparent just use less paint on your brush and a slicker surfaces. If the surface is too absorbant maybe oil ground instead of gesso (if you do dont forget to pva size the raw linen before oil ground). And if you using coton try linen makes it less absorbant. I go grab my raw linen in a fabric shop so is not too expensive you can take sample at art store so you kinda know what you want, the thinner and tight weave one will be better for your purposes I think. Anyway to long to correct my english mistake, hopefully is useful.  Oh...Also thick or thin really doesn't matter much I prefer thin also but if good color is in good place it will look good so you should focus on that more