I'm tempted to give WoW another try but after looking the new talent calculators, and other new features, it looks a little daunting/over-whelming.
To its credit, all the new systems are doled out piecemeal and the choices you can make that would screw you are obvious (e.g. a talent that has no PvE value isn't going to be enticing to a PvEer even at first glance) or are easily reversible (in theory, the intention is to switch up talents often—even on a per-boss basis—though it rarely matters enough in practice unless you're doing progression raiding or high-level PvPing).
If you do go into it, some slightly non-obvious tips:
Build the lumber mill as your first medium garrison plot. You'll need a lot of garrison resources to build everything you want and it's very easy to max out its generation while leveling up.
If you have two crafting professions and really want to get a head start on those, by all means build the corresponding profession small garrison plots, but strongly consider taking the Salvage Post as soon as you can, because it provides a lot of stuff you can vendor and use to augment your garrison followers. The way to unlock the Salvage Post is to complete the goblin questline at the southern end of Spires of Arak, so if you want to rush it, head over there as soon as you can.
In Gorgorond, choose the shredder when asked which perk you want. You get a few seconds of flying with it, which is a godsend, and many of the treasures that'll help you when you're starting out are gated by things only a shredder can clear.
Check the dungeon journal (Shift-J by default) when running instances. I don't remember if it was even in the game back when you last played, but it contains super simple single-line explanations of what you need to do when you encounter a new boss. (In MoP they were just lists of abilities and were not very useful going into a boss sight-unseen.)