Last time, I recommended starting your herbalist in the Highmountain zone of World of Warcraft Legion because of the value of Foxflower. Well, I have to say I may have been a bit premature with that statement! It still holds good unless you are an alchemist as well, in which case, you will find that your opening Alchemy quests all take you to Azsuna.
One addon I would really recommend you installing is the Gathermate2 addon - I used to use Gatherer but as of this week, it still hasn't been updated for Legion herbs. I was slow to install this addon so although I picked Foxflowers all the way through Highmountain, I don't have a record of where they all are! I fixed that for Val'sharah and Azsuna though!
One other thing to note is that if you do start with Highmountain to take advantage of the high Auction House prices of Foxflower, it is worth keeping 60 back for your Alchemist. This is another thing I messed up on so I had to go all the way back to Highmountain to pick them for my Alchemy quest! Without the Gathermate2 information, it took a while to find a good spot but I eventually found this little area in the north to be the best for picking Foxflowers.
There are lots of murlocs around here and a bunch of crab type NPC's that wander in groups so you will have to fight your way through. On the far eastern edge of the range are neutral murlocs so if you don't feel like fighting and have time, you may find enough Foxflowers in the safe area to keep you supplied.
One of the biggest changes to herbalism in Legion is the fact that each herb now has a rank attached to it so when you pick your first Foxflower, you get a simple quest to pick more Foxflowers but the quest will take some additional quest items each time you pick, then asks you to return to the Herbalism trainer in Dalaran. Once you do that, you learn rank 1 Foxflower which increases the number of herbs for each pick and the trainer gives you another quest to learn rank 2 and later rank 3.
I was also slow to do the herbing quests so I had almost finished Highmountain before I gained the rank 3 skill. But I realized halfway through Val'sharah what was happening and jumped on the herbing quests as soon as I got them! It definitely improved the number of herbs I received each time I picked too.
Next time, I'll tell you about all the fun I'm having leveling my alchemy profession!