I use elmer's stick glue to hold the fabric to the paper. (I make sure I'm using elmers because I know it is water soluble) Use a paper punch to punch a hole in the center of the hex - you can then stick a toothpick or small crochet hook in to help remove the paper later.
Some people print the hexagons on freezer paper, that will stick to fabric when ironed on.
Have fun!