^ cosign on this. you need almost NO water and wash solution to do suede. also, if its just dirt on the suede, you can use a normal pink eraser (weird I know) to get most of the dirt off if you brush lightly. Then you can use a soft brush to go over the erased area.
I always agree to try on the heel first tho. save the toe box for when you're really confident.
and for the canvas, go crazy. I've scrubbed a pair of those pretty hard with a lot of different washes and they always come out looking fine. Try not to over-soak em with water tho (blot it when done) so you don't crease em.