1 All expansion guides are written in the Battle for Azeroth beta in order to have them ready on launch day. It's important to note that betas can be buggy and unstable and may delay and even halt our progress on the guides. Furthermore, the time between the start of beta and the announced release of Battle for Azeroth is much shorter (by about 2-3 months) than past betas. As a result, our primary focus is to have the Leveling guides updated by the launch, and only if those are complete and time remains will we work on updating the remaining guides. All guides not finished in beta will be updated post launch. You can read more about this here.
Professions skills are split between expansions now, you'll have a separate skill bar for each expansion. There are still 950 profession levels in total, just that there is no one single progress bar with 1 to 950 for it anymore. Instead, there are 8 separate progress bars. (The only exception is Archaeology, because it will still have a 1-950 progress bar)
Level your hero. You need to start leveling him from the moment you have 2-3 units. This isn’t necessary. If you have KotG, DH, BM, FS, or AM you don’t even have to wait for units. However, with the help of units, your hero can very easily overcome creeps. Among players there is a certain understanding – creeping. Creeping is the destruction of neutral units in order to gain experience. If you kill a creep you earn gold. A gold number and a plus sign will appear on the screen. Sometimes, you need to kill them in order to earn more gold for building purposes.