Well, here's also an article on industry friend Scott F's T-Biz network to get you started.
http://t-biznetwork.com/articles/screen-printing-heat-transfers/To be honest, I haven't checked out this particular one yet, and don't know if it's an updated version of what used to be on the old TSPMB and site or not.
One thing that makes this process a lot easier is a vacuum board to hold down your paper. whether an add-on to a shirt press, or as part of a stand-alone set-up with jiffy clamped screens.
That system would print multi-color like most flat stock, as one color printed and cured or dried at a time, while some have success on a shirt press printing all colors before curing, with flashes in-between.
I'm also, as you probably noticed, moving this to the Heat Seal section where we are also presently discussing another member's first attempts and problems.
