Don't Paint Around Stuff If You Don't Have To
Here I'm posting how I wash in color, dry, then use a stencil and Mr. Clean's Magic Eraser to lift out the geese. Dry well and paint the geese.
Washes of color are difficult enough without having to paint around things, or even have your paint not flow freely because you masked something out. Think about where you could use a stencil. I use them a lot, so I can get smooth, interesting washes of color.
The biggest issue students have is that they overscrub their paper when using the stencil. It doesn't have to go back to pure white - you can use opaque white. The surface of your paper is important, so don't mess it up.