In FFI explore every cave and town and talk to everyone. It might seem a bit tedious but that was the done thing back then. Aside from that you'll definitely need the experience gained from all that wandering around to stand a chance of surviving. Places like Mt. Gulg and the Ice Cave will have you wishing you had more spell charges, because just when you think you're getting somewhere: dead end. Or the floor literally kills you.
The explore everything requirement gets toned down a lot after FFIII but for the most part it still applies. In VI you shouldn't really be stuck for places to go until probably after about halfway through the game, where there are multiple options for you to do in any order. There are 3 fairly well hidden characters though. As for VII, aside from one or two parts in the main story where you're required to search for locations, it's fairly straightforward.
And I can't remember whether Yuffie & Vincent are mentioned prior to meeting them. Vincent might come up during the Lost Number sidequest. The people in either Fort Condor or Junon might tell you about Yuffie. I honestly can't remember.
The explore everything requirement gets toned down a lot after FFIII but for the most part it still applies. In VI you shouldn't really be stuck for places to go until probably after about halfway through the game, where there are multiple options for you to do in any order. There are 3 fairly well hidden characters though. As for VII, aside from one or two parts in the main story where you're required to search for locations, it's fairly straightforward.
And I can't remember whether Yuffie & Vincent are mentioned prior to meeting them. Vincent might come up during the Lost Number sidequest. The people in either Fort Condor or Junon might tell you about Yuffie. I honestly can't remember.