I recently started playing again with my purchase of BFA I used a 110 character boost on a horde character and I cant figure out how to even start to unlock the allied races.
Most have requirements that require some playing through other stuff. Check this guide out for the overview:
110 boosts have some of the Legion content already unlocked. So, that character will already have Legion world quests unlocked, as well as the Broken Shore. The first few quests for Suramar are also marked as completed.
So, what that means for the Legion-introduced allied races:
(1) Highmountain — Nothing much changes here. Once you get your class hall open (I can’t remember where boosts are with that) pick the Highmountain zone to quest in, and do al the quests there. (And also do any world quests there as they come up for the rep.)
(2) Nightborn — Take the flightpath to Meridil, and go into the cave just to the north of the flightpath. You should be able to pick up the beginning of the questling there. You basically need to do everything in Suramar. There’s a lot of questing here, and some areas of the city are just nasty at level. I’d strongly recommend hitting 120 before doing the bulk of it. There’s like 10-15 hours of questing (at 120) to get through, but the good news is you’ll get most of the rep you need through the questing.
(3) Lightforged Draenai and Void Elves — You can jump right to picking up “The Hand of Fate” from Khadgar in the Violet Citadel in Legion Dalaran. That’s the starter quest for Argus. You’ll need to complete all the content there (as well as clear out world quests for rep.) At one point, you’ll get some quests that aren’t reasonably soloable at 110, including killing a high hitpoint world boss. So, again, leveling to 120 first will make things a lot faster. At 120, it’s 3-4 hours worth of questing to get the achievement, then a couple of weeks of world quests to grind out the rep.
For the BfA-based allied races, the 110 boost should lead you into the BfA content. You’ll need to do the main storylines for the 3 leveling zones for your factions and the War Campaign as part of the Various unlocks needed.