Improper leveling of your production profession skills can cost a small fortune. Heck, even proper leveling of some production skills can cost a small fortune. And keep in mind that equipment you produce using your profession will typically be slightly worse than equipment otherwise obtainable at your level via the Auction House and/or instances. It is therefore strongly recommended not to take on a production trade skill until you hit at least level 30, or better yet, level 70+. However, if you are determined to take on such a profession (particularly under level 30), read a suitable leveling guide in order to gain whatever skill level you desire for the least amount of money.
Just before Battle for Azeroth goes live, you will want to log all of your characters out in the zone of Silithus so that you can acquire the quest to talk to Magni and obtain your Heart of Azeroth (refer to our Heart of Azeroth guide for more information about this item). This is the new artifact-type of piece of equipment that you will use for all of the Battle for Azeroth expansion. Once you acquire your permanent neck slot piece of equipment, get back to Stormwind or Orgrimmar to begin your scenario that leads into the introductory areas of Kul Tiras and Zandalar.