Congratulations on reaching Level 120! There are a myriad of new things to do. The first thing you should do is head to your faction hub ship where you have been doing your mission table quests and footholds to pick up and complete the quests necessary to unlock World Quests. World Quests will provide you an opportunity to grind reputation levels, acquire gear, and gather Azerite. There are tons of new things to do that we will cover in our Level 120 Battle Guide found here: Level 120 Battle Guide.
The steps from section two should be utilized and repeated until you reach about 25,000 gold. Once you hit that mark, two more options become available to you, the neutral auction house and cross-realm transferring. The latter is the single most effective way of making gold, although much planning must be done prior to it. However, the smaller methods you used to hit 25,000 should still be done as regularly as before. Nobody got to the cap with only BoE epics, it takes time and patience!
The Horde levels 50-60 guide has been rewritten and revamped. My 1-60 Horde leveling guide is now completely updated for the 1.12 Drums of War patch. As you can see it is about 15% larger than the 40-50 guide (single largest guide page yet). There is also a lot of route changes. I moved the entire Silithus section from level 55 to level 58, which allowed me to include a lot more quests for that zone. There is also a lot of other improvement to the route, including adding a lot more quests into the guide, mostly from Moonglade, Silithus and Eastern Plaguelands. This will make the final level 59 grind much shorter.
Island expeditions - Set sail for the previously unmapped isles of Azeroth. Battle in groups of three as you race against cunning rival intruders—or enemy players—to collect the island's resources. Constantly evolving challenges await as you traverse frozen landscapes near Northrend, open the gates of an abandoned Gilnean castle, navigate a war between elementals and more. Can be done either in PvP or PvE against advanced AIs.
Leatherworking is a crafting profession that uses various leathers obtained from skinning to craft leather and mail armor. You can make gold shuffling leather into enchanting materials through the rank 3 bracer recipes. Battlebound for Stormscale and Warhide for Stonehide Leather. The other main market for Leatherworking is crafting the item level 850 gear. I find that both Dreadleather and Gravenscale gear sells very well.
Once again, as soon as you hit 70 - I recommend to go and learn faster flying. This speeds up your questing A LOT, and is worth the time and gold. It will cost 4500 if you go to the capitol, or 5000 if you prefer Shattrath/Dalaran, because you will not have reputation with them at that point. This price will sadly be above what a totally new character can afford, if you don't have any Main. But you should go and buy flying as soon as you have enough money.
Get exalted reputation with every faction you can. This relates to the previous two pretty directly. Gaining reputation with most of the factions of Kul Tiras and Zandalar will allow them to sell you high-level gear, while gaining reputation with the Champions of Azeroth faction will grant you levels for your Heart of Azeroth, the neck piece where all of your AP is stored.
Guide to Obtaining and Selling the WoW Token Buying and selling the WoW Token, which allows players to buy game time with gold, or make extra gold by selling the token on the Auction House. What is Blizzard (Battle.net) Balance Overview of Blizzard (Battle.net) Balance, a currency used to buy Blizzard Entertainment products including World of Warcraft character services. How to Purchase World of Warcraft Game Time The cost of a WoW game time subscription, how to acquire a subscription, gift one, and cancel it, as well as how to play WoW for free.