Always, and I mean always, wear an apron or old clothes. Cherry juice is a natural dye, and it will laugh at your favorite white T-shirt. It is a beautiful stain, but still a stain.
Also, work over a bowl to catch all the juice. That bright red liquid is pure gold for cocktails, lemonade, or drizzling over ice cream. Do not let it go to waste.
And here is a hard truth: not every pit comes out cleanly. Sometimes a cherry fights back. That is okay. Just pick the pit out with your fingers and move on.