To make the leprechaun, paint the fingers orange to create a beard. Then use a peach color to paint half the palm making a face. Next, paint a strip of orange hair. Lastly, paint the rest of the palm & thumb green creating a hat. Now your ready to press it onto the paper! It would also look good having the fingers closed instead of open to make it resemble a beard even more.
To make the rainbow, finger paint the colors of the rainbow. Then paint each pointer finger blue & dab a bunch of dots on each end of the rainbow to create clouds.
Don't forget to check out the one I made with my son when he was 1! It includes a fun poem as well!