Herbalism + Mining worth it for XP while leveling?

I'll soon be returning to the game with a friend. We will create fresh level 1 characters and wear full heirloom sets for max. XP bonus.

I hear that herbalism and mining gives some XP for each herb/mine you handle.

So, is herbalism + mining worth just for the sake of leveling faster?
Yes. At many levels, you get more XP from a node than from killing a mob. It doesn't change your whole questing experience, or anything like that, but it's a small boost. And with two of you together, you can both loot the same node now.
That's a great answer - thanks!

Any other nice-to-know-tips for faster leveling?
20-60: Stay in the former level 20-30 zones as much as possible, and milk them, since they scale. You get as much XP, with less travel time.

60-80: It's a swamp. Gonna feel slow no matter what you do. Blizzard closed all the loopholes that were available for speeding levelling up here.

80-85: Goes by in a flash. Everything works. (Except Dungeons)

90-100: You can skip the Draenor entry experience with a portal to Ashran, or by a cave beneath Timeless Isle. With looms, you don't need the gear from there. Buy the +10% XP potions from the Garrison. If you already have Draenor flying, picking treasures in Draenor gives as much XP as questing. Addon HandyNotes with DraenorTreasures module shows you where. Apart from Treasures, you can get through almost entirely with Bonus areas.

100-110: Legion Assaults, but only one every 18 hours. Great if you're bringing up an alt while you play your main, not great if you're focused on levelling. Quest away.

110-120: Quest your heart out. Make sure to get at least Friendly rep in all three zones, since you'll need it for World Quests. Do your War Campaign and set up your Outposts. Do the Island Expedition Training quest you get at ... 116 I think. All of that is in preparation for what you need to unlock at 120. You will need Loremaster of all three zones for BfA flying, eventually.

Quests vs Dungeons: I don't know. Different people report different experiences at different levels. Some say only worth doing once for the quests. Some say still marginally worth doing random. Nobody's producing convincing numbers for either opinion. I'm personally convinced dungeons past 80 are a waste of time, until you get into BfA, when you can do dungeons for the guaranteed gear at the end of every zone.
05/11/2018 09:55Posted by Gráinne
100-110: Legion Assaults, but only one every 18 hours. Great if you're bringing up an alt while you play your main, not great if you're focused on levelling.

Wowhead's front page tells you where and when they are available. If you do them all it will get you at least a level each time and you can do them until 111 at least.