Very cool tip the "bottle suck". I used to do that as kid for fun. If you use a glass bottle, you can suck a vacuum and them when you release your epiglottis, the air gets sucked back in with your tongue. For some reason I thought that was funny back then
Only a couple of weeks a go I realized that that's actually pretty much the same thing as packing...
Laminar is absolutely right about the empty lung thing. That's not the best way to practise it, but I find it a good way to "verify", if it really works like it's supposed to. When you get it right on empty, it's feels so obvious that there's no question about it. Before that I used to wonder if I really got it or not.
I know a lot of people have dedicated months or even years to this, so patience is the key
(I was lucky enough to have tons of ear infections and to be stupid enough to suck bottles to vacuum, which propably helped in later years)
