You'll only learn the new things in raids like "tank swapping/taunt swapping" by doing them, they're super slow paced and predictable on normal mode and lfr DS, they're also easiest encounters this expac to learn them.
I'd suggest using omen for a while to get used to being aware of your own threat along with the other tank's, it might not be required to hold threat but you have to learn to share the threat table while staying above all the dps, you can taunt for when you need agro but if the tank dies and you're second threat that can save a dps and maybe a wipe.
All the new mechanics you have to learn are simple, you just have to throw yourself in and try it once or twice. So what if you get kicked from an lfr, you can requeue and get more practice on the same fight. Before long they'll be second nature to you just like knowing where trash spawns and when you need to use more cds to help your random healer in 5mans.
Treat your big cds like they are sacred if you know you will need them for a one shot ability, none of that trigger happy stuff or hoping it will be back up in time. Keybinding them is a very important thing to do, I've known tanks that intentionally don't bind just their cds, they click them instead.
Your fellow tank in whichever group you have will 95% of the time be happy to help you, ask him any questions you have and tell him that you're new to tanking raids, he will likely be able to give you tips and will be the best one by far to evaluate your performance and tell you where you need to improve. If you hold threat and don't get one shot you are doing your job and shouldn't worry about getting kicked or being raged at.
Going in and dpsing an lfr if you haven't would also help, you'll get a feel for everything and make you aware of where dps would like things tanked.