A big thanks to Jess of Craftiness is not optional for her great inspiration!
My first attempt wasn't so successful but after that I decided that unlike Jess I would use heat 'n' bond to attach the applique (I just used a pressing cloth so I didn't stick to the shiny fabric). I also used clear thread on top and was much happier with the result.
My daughter is thrilled and can't wait to give the shirts to all her friends. :)