I have been meaning to put together this tutorial for years now. That's not me exaggerating either. My first applique set was released in 2013.I now have 6 sets of 12 appliques and am currently working on the 7th. You can find them all here: http://www.ravelry.com/stores/teri-heathcote-designs
This tutorial will show you how to attach the appliques to the blocks without the stitching showing through the back.
I use this technique on all my blankets as I think it gives the back a really nice clean look. Even though that is not the side you will be looking at, it is nice to have a professional finish .