have a good partner and practice a lot. I startet as a pvp newb with a shaman mate , at first we were total newbs, and made our way to 2.3 and multi duellant in tbc /wotlk. Even got a 5vs5 with 2.4 k on a strong streak and gladi. Last time i played arena with some ambition was i think pandaria or so, nowadays i dont have any pvp oriented friends in wow anymore.
If u want to "random" your way up, i recommend joining as a healer. On my shaman, i can get 1800 rating with just everyone in 2ws, its just a matter of time. If other guy from dungeon finder is good, it spikes up to 2 k pretty quickly, can be done in one evening.
But going further requires a lot of small important micromanagment stuff and communication with teamspeak, and practice with the same guy. People have gotten very good In arenas, its not like it was in tbc, if u make very little mistakes or non ideal plays in high dampening scenarios, u will loose those matches to similar skilled, but a little more experienced teams, even if u are a legacy duellant / gladi player. This can be straining on your motivation and teamintern relationship
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