Hi Dana, welcome to the board!
Which practice head do you have. I tried one, but it isn't the same as on a real person. It was good for getting the general layout, but it seemed like my lines and blending suffered for it.
I think the swimming would be great for you, then you get to do it twice, before and after the water!! Just kidding, I can imagine the multicolored water in the pool, eventually turning to grey.
I have a Rogue Planet practice head that I got on a discount makeup site...it's plastic so it's different than most practice heads out there (in that you have to do multiple coats of paint for the color to really show), but it's good for what it's meant for.