I think she did a wonderful job, considering this is the first time she painted on glass. It really is not that hard, but you really do need to get the feel for it by experimenting with the different paints on the market. What I like to work with, may not be what someone else would like. There can be a lot of trial and error before you get the outcome the way you want.
The best thing about painting on glass is, if you make a mistake just wash it off and start over. It really is as easy as that.
Remember to have fun!