Target priority is a HUGE thing for me, both as tank and DPS. Let's say you pull 6 mobs, 5 of which are just basic smackers, one that uses a partywide damaging attack... I'll mark the AOE one for first kill just so the healer does not need to worry about that target anymore, as well as reducing the load placed on the party by doing that. Once it is dead, have fun and murder the rest... Just understand the most dangerous things in any certain pull, clean it out first, then move onto the rest, be it single or AOE.