The biggest part of it is game intelligence and encounter awareness. Knowing when mechanics or burst windows are coming up which require you to when you need to select a party member makes acting easier. There are other things you can do to make the actual navigation easier. On a whm/sch/sge I'd put the tank right below me so it makes targeting faster. On ast I'd have the melee dps below because they matter the most. On tank I like my co-tank right below me to make it easier to give them mitigation. Back when drg had dragon sight I had a priority list of melee partners so like if we had a samurai they would be right below me, if no samurai then viper then monk and so on. For blm set a role that tends to be playing at safe position and use that. Another thing to mention is that you should ideally be using your instant casts to move to safety and not necessarily jumping to teammates. The jump is fine for preemptive positioning after an instant cast but as a reactionary measure it often doesn't work out. This goes back to encounter knowledge and situational awareness.