I spent lots of time online learning about how to paint on glass worried about how it would work. What I learned is if you first block the whole thing out with white eggshell paint from the hardware store and then paint with craft acrylics the colors will show up more vividly and wash off more easily. I really sweated it ahead of time so this preparation of learning through all those YouTube artists who put their tutorials out there for free was almost like apprenticing. Here is the one I did on my dining room window. I let it sit almost a week and it washed right off.