Ok so as I mentioned yesterday, I wanted to try using freezer paper to stencil. This was the tutorial I used.
I'm going to include my own pictures below to show how my first tries went. My suggestion is to be sure you've pressed it completely with the iron before painting and paint soon after ironing. I think that caused some of my edges to lift- I waited a few hours after ironing (waiting for my son to get home). I also used transfer paper to move my stencil which a lot of tutorials didn't show, but it made it easier to not mess up the teeny pieces that go inside letters or whatever.
I painted the little brother onesie-- I needed to paint thicker to make sure the letters were thoroughly colored.
I let my son paint the green train one. He had a great time and I tried very hard not to make it look "right". :)