This is a website that my friend found, and we're randomly doing this. Basically all it is, is you write something on a piece of paper like 'Your Beauitful' or 'You look Amazing' or just something nice. All you need is a pen, a piece of paper, and tape. Hell, get post it notes and then all you need is a pen!
http://operationbeautiful.com/about-2/
I think it would be really cool if more people would help out.