Like with addons in the current game, you just need to drop any of these addons into the addons folder — find it under /Interface/AddOns/ in the Classic beta folder, which is in your World of Warcraft folder by default. Then once you log on to the game, you’ll want to make sure that the addons are enabled via the menu option on the character screen.

Vol’Dun is the hardest and most tedious of the Horde Zones in Battle for Azeroth. It’s also probably the one that makes the most sense. Each sections of quests leads directly to the one you should do next. For all of these reasons it’s going to be best to get this one done early. Thanks to any legendary items you might have collected in Legion, you’ll be strongest in the leveling process before 115 and weaker after — because that’s when the legendary effects stop working.
If you're looking for simple, just get actionator. Set it to undercut everything you post for 1c and alt click from your bags. It will place the item on the ah window, do a scan for that item and autoset the price for how much you told to undercut (you can change it accordingly if you feel like it). It will remember if you do stacks for which items and replicate it everytime.
Common methods of power leveling include doing only those quests which are most efficient in terms of experience over time, and analyzing the quests in a given zone so as to do them in the most efficient order possible. Remember, the idea of power leveling is speed and efficiency--you may wish to obtain an addon that will show you how much experience per hour you are gaining to test your techniques. Additionally, ensure your character's talent build is crafted for maximum endurance. You want as little downtime (walking, drinking, eating, crafting, typing, etc.) as possible.
Our old friend Quest Helper isn’t updated for the client, but there’s !Questie and MonkeyQuest to help you track available quests and their objectives. The biggest challenge to leveling up in the beta is searching for where the quest objectives are, so if you’re looking to hit the level 30 cap fast — or just the level 5 cap in today’s stress test — you’ll need one of these. 

Most classes in World of Warcraft start at first level, but Death Knights and Demon Hunters are exceptions. They start at level 55 and 98, respectively. This alone can shave a huge chunk of time from your leveling experience. Of course, it only works if you want to play a Death Knight or Demon Hunter, but they’re both solid classics that can dish out damage or tank in a group.
Let's face it, World of Warcraft has an awful lot of content available, especially when it comes to end game content. Unfortunately, that can quite time consuming and not everyone can afford to spend so much time getting there. Wouldn't it be great if there was a way to skip all the grueling and time-consuming leveling process and just jump right into the end game? Thankfully, there is - WoW leveling service!
Pick a simple goal or idea for your AddOn. It's often a good idea to just make an AddOn that only opens a window or prints a message to get started, especially when everything is new for you. After that works the way it should, and you have learned everything necessary to make an AddOn work at all, you can move on to adding one piece at a time toward your goals. Writting software in general is often a never ending process because you can always think of something new to add or improve.
At level 80, I skipped Cataclysm and went straight to Pandaria. Even as my warrior leveled up, and that heirloom axe increased in iLvl along with me, Dugi still ranked that iLvl 87 sword higher. I kept picking up new 2h weapons, and Dugi kept rejecting them in favor of that Wrath sword. That's when I noticed that all of these Pandaria weapon drops, even weapons 20 iLvls higher than the Wrath sword, had secondaries under 20. So even though Dugi Gear Advisor is showing that a new weapon would provide a DPS increase, it still prompts me to re-equip that Wrath sword every time I equip a new weapon. Meanwhile, I've kept the heirloom axe in my bags, assuming that at some point its stats would once again beat whatever I had equipped, but nope, it doesn't, according to Dugi.
What am I supposed to do now? Is there a way to get the curse client working again? I've googled it but haven't found any useful results. Do I have to uninstall & re-install it from scratch? Has the Curse client been taken permanently offline, meaning that it's no longer viable software? Do I have to install a Twitch client and manage my WoW addons from there? If so, do I have to re-install all my addons from scratch, or will they somehow carry over from Curse to Twitch?