Step 1: Get the last passive from the Warrior Guild Skilltree and obtain the Quest to kill Blackdagger NPC's (cancel other Quests till you get the BD Kill Q)
Step 2: Choose a Empty PvP Server and be sure your Faction captured the Outpost
Step 3: ???
Step 4: Profit
Nice and fast EXP for the last levels to 50 and only takes about 6 min for a Repeatable Quest + 200 Gold.
P.S : Warrior Guild Headhunter Questgivers are in every Inn in Cyrodiil
-