The CDC is suggesting that all masks allow for breathing without restriction, fit snugly but comfortably and include multiple layers of fabric.
Be cautious of "Tightly woven cotton cloth. It should not be a looser weave like the material or knit a sweater is made out of. The holes in that type of material are much too large. It suggest that we should not buy anything too thick that can restrict breathing.
The CDC also suggest that we don't go more than 2 days without cleaning your mask.