You have to be facing the target you want. With no other targets selected and it will get you on the closest target. You use macros for specific targeting action such as /assist. There is also target filter that give you 4 customized targeting options. The only unavoidable miss target i tend to deal with are egi's and carbuncales cause the game counts them as enemies. And no matter what you do will target them first. Npc's seem to fit in there as well but you can filter them out its just the pets that piss me off.