Well let me put it this way, it's amazing that you are looking up guides on specific classes, wish a lot more players would do that. But the truth to be told is, that it matters at level 60.

Before people now throw stones at me, of course you should be learning your class/job and the skills that go along with it, instead of just pushing/clicking 3 buttons.

However, most guides out there are made for end game content or at least level 50 and do not even apply to lower levels. Some are purely build around raiding. You won't have the gear and skills even unlocked to follow any of these guides. I see many times new players pretty much apologizing in content like bray flox, for not having 1k+ dmg etc. that they saw somewhere on youtube or twitch, making them feel bad.

With that said, I think you should look at the class you're trying to play and figure out the basics, before even attempting to watch "guides". Most jobs are self explanatory at lower levels and reading the descriptions is all you need in most cases. Just enjoy the game and learn about perfect rotations when it's time..... level 50 (without HW), 60 (with HW) and not at level 20+.