Hi, im currently level 21, i did all of the undead starting zone, and some of the troll. At level 13 i went to the crossroads and did those, ratchet, camp taurajo and some of stone talon mountain.
I have no clue where i should be going, i dont see any more quest hubs. Some guidance would be appreciated!
This link may be useful!
Prob Hillsbrad or Ashenvale?
At that level might want to try to get the bfd quests ready and some of ashenvale. Dungeon quests give alot of exp.
Thank you brother, when i look at ashenvale or hillsbrad i just dont see that many quests to do lol
You have a bunch of zones that have quests in your level range.
Ashenvale, Hillsbrad Foothills, Stone Talon Mountains, Thousand Needles, Barrens, probably a few in Silverpine Forrest still. You also have the dungeons and for Horde you should have quests for Wailing Caverns, Shadowfang Keep and Blackfathom Deeps in this range’ish.
Download the Questie addon if you don’t have it. I have a feeling you missed a bunch because you should be out-leveling these places with quests in your log still.
At 21 theres room for you in Shadowfang Keep. The +Stamina ring there is certainly worth going through the dungeon at least once if you haven’t already
I would say do the higher level quests in silverpine (including SFK as suggested above if you can) then the low level quests in hillsbrad. (If you’re on hardcore though, Hillsbrad quests that involve going into enemy towns / bases are very risky for their level.)
You can also run wailing Caverns before leaving the barrens if you haven’t.
When hillsbrad becomes too difficult go back to Kalimdor and do anything in Ashenvale, southern Barrens and thousand needles till around level 30.
I had this issue as well, hard to figure out where to level except if you google it 
There’s a number of guides you can use or download that can hold your hand a bit on where to go specifically.
Other than that, you should be getting some “bread crumb” quests that send you out and about.
At 21 for Horde, you are looking primarily at southern barrens, stone talon, hillsbarad, and/or ashenvale for quests. If you’re on a pvp realm and those zones are super rough (hillsbarad tends to be awful out side of super late night/off peak hours), you can grind mobs in the southern barrens at nearly the same speed until 30 or so (but even if you really enjoy grinding and trying to keep a low profile from wpvp you’re probably still better off hitting 1k needles at like 26)
Alternatively, just explore places, many times the roads are safe…ish. just ran through two too-high level zones and found an appropriate place.
For example taking the zepplins and boats around to collect flight paths usually uncovers something.
Also quests often come from your big hub cities as they become possible, which tends to point you in the right direction.
heard Chatgpt has an ok lvling guide also lol