This is a fun thing to do,when i'm at my desk i try and never throw paint away once i finish doing a picture or project.
so, i had black ink in a little bowl and some left over colors on my pallete, i dipped my thumb in the ink, then swirled it around my pallete, then dipped it in my little water glass for a second, letting it get pretty wet, then i took it to clean sheet of paper and started making some abstract shapes. i did about 10 or fifteen pages of abstract finger doodles.
once the papers dry, you start seeing things in the abstract shapes and just start pulling and pushing the value and form until you get a nice image!
this is very little work, so you can see smudges and fingerprints if you look closely
and this one, you wouldnt ever know i used my finger, cause i went in with goache and other stuff, and it all got covered up.
so with 10 or fifteen or whatever i came out with 2 cool drawings, nice! i recommend letting randomness and accidents happen because you start exploring new shapes and its very fun