The forum at UMAi's website has great information for newbys -
https://www.drybagsteak.com/forum Some of the most important points I've found:
1. Don't use meat that has been mechanically "tenderized", it will rot.
2. Best bet is still in the cryo bag; you can drain the liquid, but don't wipe it down; you want the surface wet.
3. I don't understand why, but it is impossible to get nearly as much air out of these as regular FoodSaver bags. The forum has discussions and photos of what is acceptable.
4. There is some disagreement in the literature about turning it once in a while; I have come down in the "fat side down, don't touch it" camp.
My own recent innovation is using a couple cups of sugar in ziplock bags to weigh down the bag for a couple days to encourage the bag to stick. They will be removed to allow the membrane to function properly.