There are few things you should definitely have with you to make your leveling experience even faster.
First and foremost make sure you EMPTY your bags. Also if you can afford it buy 3 Hexweave bags or 3 Royal Satchels. Why 3? Well you will get a 26 slot bag as a quest reward in Highmountains – Addie’s Ink-Stained Satchel
Make sure you have flasks. Get the appropriate flask for your class type. So for example if you are agility type class pick flasks that give agility. These are the 3 flasks you need to get according to your class:
Greater Draenic Agility Flask
Greater Draenic Intelligence Flask
Greater Draenic Strength Flask
If you already have Empowered Augment Rune use it, however if you don’t have it in my opinion it’s not worth buying it because it cost too much gold and you will only be using it while you level. Once you hit level 100 you won’t be using it anymore because you will be using Defiled Augment Rune instead.
Get yourself some Goblin Glider Kit’s – Those will save you a lot of time waiting on lifts or having to run around.
Mecha-Blast Rocket – Bare in mind that this one share CD’s with potions and other similar items(1 min CD)
Also as stag suggested in the comments below you could get:
Drums of Fury
Draenic Invisilibty Potion – or any other invisibility potion. Basically whatever is cheaper on the Auction House, you can use that, but by logic this one should be the cheapest.
Draenic Agility Potion
Draenic Intellect Potion
Draenic Strength Potion
Also at the beginning of the expansion you probably won’t be able to get your hands on these, but after few days you should be able to buy them from the auction house.
Also make sure you pick your professions, since professions in Legion have quite a few quests that give xp. Pick all your main professions and your secondary professions as well.
I recommend you get these Addons. They can definitely make your life easier:
Daily Global Check – It tracks your daily/weekly activities. It’s really helpful if you use more than 1 character.
HandyNotes – required, so that Nandy Notes Legion can work
NandyNotes Legion – This addon will show Legion Treasures and Rare Spawns on the map & mini map.
Atlas Dungeon Location – This addon will help you find where dungeons are.
Note: Don’t forget to update the addons on launch and after big patches!!!
In previous expansions people would usually complete 25 dailies and turn them in once the expansion comes out, however now things are different. Why? Well Draenor dailies in legion give 3750xp atm which is…. bad, so here are your options.
1. First option is if you have any quests in Nagrand/Spires of Arak to complete them, but don’t turn them in. Once the expansion comes out you can turn them in for some nice xp boost at the beginning. Also if you have some uncomplited bonus objectives in Nagrand/Spites of Arak you should almost complete them(leave 1 mob alive, so when the expansion comes out all you have to do is kill 1 mob and continue to the next objective)
2. Second option if you don’t have any quests and objectives left is to get the Missives which are sold in your garrison. There are 14 missives which equals to 14 quests. Each of these quests give 3750xp + you can also do the daily quests in Tanaan Jungle. There are 5-7 quests there. Generally you can pick 5 quests daily, but if you check daily you should be able to get the other 2 daily quests which rotate. So if you do the missives + 5 tanaan jungle that’s 71500xp. It’s not much, but it’s still a decent boost and it will only take you like 1 minute to turn them all in.
3. Third option is to combine option 1 and 2. If you have few quests/objectives that aren’t completed you can do them + fill the rest with the missives/tanaan dailies.
Note: If you have Draenor Pathfinder achievement and you can fly in Draenor you can also fly around and gather the few missing treasures that you haven’t picked in Nagrand/Tanaan for some extra experience, but in my opinion it’s not worth it. You should do this only if on launch day(few days afterwards included) there are some major lag/bug issues and you can’t start normal leveling in the Broken isles(Legion zones).
If I can think of/find any other worthwhile preparationg information I’ll update this post, so feel free to check it every once in awhile