Don,
I have the same issue with many flake tobaccos. It took me a while and lots of practice to get it right. I still struggle on occasion when trying a new flake or in a pipe I haven't smoked flakes before. So patience and practice are the best recommendation.
I echo what SD said on the SG flakes. They require a lot of drying time. I then usually fold them and rub them out between my hands. The Peterson Irish Flake I have requires less drying, maybe an hour, and has been working for me with fold and stuff method. Roughen up the seam of the fold and the top a bit to break out the fibers and improve air flow. I also have C&D Sunday Picnic (Highly recommended) and that one is very much like the Peterson flakes with regards to moisture and how I pack them.
Good luck.