Start with a variety of jelly crystals that have distinct smells...
Or if your lucky enough to get your hands on some American Kool-Aid it works much better as it is more a powder than crystals so dissolves easier and glides on paper better. We found this packet at an old fashioned lolly shop
Pour jelly crystals into pots and combine with boiling water, your after a thick consistancy like jam but try to dissolve as many of the crystals as possible
Paint away! We found the texture of cardstock(available at scrapbooking shops) works well as it has something to stick to. Try to keep your colours seperate so you can smell the difference when finished