We've talked about taping down the paper as your kids are painting or drawing to make the whole experience easier for little hands. I've used masking tape loops on the back of paper, but there's another tricky thing you can do.
If you use thick paper (like watercolor paper or card stock), tape down the paper all the way around the edge by using masking tape on the front. Try to get these pieces semi-straight and uniform.
When the artwork is all done and DRY, carefully peel the masking tape off. It creates a nice white space around the edge of the artwork and really makes it pop.
Have your kiddo sign their work along with their age. Voila!