About tanking, well as you see the dps while tanking is fairly easy.
But you do have other things to Watch for as tank.
And you maybe have played warrior for awile and it comes naturaly that you know that class more then blm.
DPS in other hand we have to focus the our skills, roations, adjusting and alot of otimizing while Dodge mechnics on the bosses.
"yes i still see alot of people don't do this"

My tips sounds very dull but its simpel, practis, practis and even more practis.
Read some roations guides im pretty sure alot of blm players have tips and tricks what they do.

Noone is very good DPS with there class at begining, keep practise makes you perfect.
I start with dummie to learn openers and then try the timed dummies challange to see if able to beat it, then i try out them in dungeons / trails.

Just keep playing eventully you be master blm like many who playing it!