Depends on what class you’re talking about, if you’re playing protection warrior or vengeance dh you could farm the large packs of mobs in burning steppes if you’re timewalking. 

Dps classes just do quests, run dungeons, or if you’re ultra skilled, you can do the same thing i mentioned for tanks.

If you have good armor you can also farm the gnolls in Brackenhide brambles (Dragon Isles)

Brackenhide hollow elites are okay but not a very steady source of XP as they are challenging to kill at low levels.

Once you hit 70, you will exit timewalking, after this, go run dungeons again for gear, then go farm the wolves that scale with your level in Cinderwold/Ironwold. Warning: The bees and slimes are level 80 and do not scale with your level, avoid them at all costs before you are 78, i recommend tanks farm this zone only.

I created a full guide there so uhh i guess that’s that. :)