Pushing rhinestones even through thin leather can be a struggle. Especially 28 of them. Mark your placement (in reverse) on the back side of the leather. I recommend doing the rhinestones before adding the fleece lining to the leather.
Indent the leather with the prongs, but then go back and poke holes all the way through with a sharp pin. This will make pushing the prongs through much easier. Also, if you can find them, I recommend the rhinestone holders with long prongs.
I'm using size 7mm rhinestones and size 30 holders.
I secure the stones with a drop of Aleene's Jewel-It glue. Wipe off any excess after placing the stone and let it dry at least an hour before messing with the prongs.
Try to bend the entire prong inwards, down to the tips - you should be able to run your finger over it without feeling poked. Prongs not bent all the way down are likely to snag on... just about everything.