Cool, I love talking about job combos in this game. I feel I've gotten pretty close to a perfect party setup.

Faris makes a good choice for a thief. Don't feel like you have to master it right away though since she's not going to be a freelancer until the end of the game anyway. You'll want to switch her to other stuff after new jobs open up with more crystals. I'll go more into detail on what I do with Faris later.

For now, let's start with Bartz. The best strategy I've found for him is to take knight to level 3 to get the dbl grip ability, then switch to a blue mage with dbl grip. The blue mage has somewhat mediocre stats but can use swords, and dbl grip lets you hold a sword in both hands to double attack power. This means Bartz will be an extremely strong physical attacker who can also cast and learn blue magic. I highly recommend you look up a guide for which enemies you can learn blue magic from, as you can get a ton of useful spells to inflict wind element, water element, fire, blind, frog, stun, healing, and level-based damage among other things. By the end of the game it's worth having just for Mighty Guard and White Wind alone. While blue magic isn't always useful in every fight or every turn, that's why it's so perfect on Bartz; most of the time he can just attack and save his MP for when it becomes applicable. After he masters blue mage I switch him to a dragoon with Blue secondary. He has to temporarily switch the learning ability in when he's fighting an enemy that can teach him a new spell though, or just switch to freelancer where he'll have it innately. Endgame I like to have him master ninja and dual-wield katanas with x-fight and blue magic. He doesn't really need magic sword like many other flowchart builds will recommend because the katanas can crit for double damage.

So concerning Faris, I use her as a ninja for the bulk of the game after it becomes available. Once you unlock it, you can switch her to it from thief and you'll see her transform much more into the damage-dealer you want her to be. However, being the other physical-based character in the group means she's another great choice for utility options, the main two being time magic and CONTROL. Control is one of the best abilities in the game: not only is it mandatory to be able to learn some of the best blue magic spells, but it also has incredible utility in most fights because it allows you to completely nullify dangerous enemies in a group, preventing them from attacking your party while the other characters kill the weaker enemies and even using the dangerous enemy's abilities to your advantage. Once she learns control from beastmaster, it's the perfect secondary ability to both ninja and time mage. Try to gradually level up time mage to whatever level the highest spells you've bought for it is, as it's great in boss fights. Control secondary and equipping the heal staff make time mage Faris a great support character and ideal for when you're leveling up summoner on Lenna (more on that later). Then switch her back to grinding ninja, using control secondary for normal fights and time magic secondary for boss fights to cast haste, float, etc. Once she's mastered ninja and time mage (which is usually close to the endgame), I'll switch her to a dual-wielding mystic knight and have her master that too. So for endgame as a freelancer she can dual-wield knight swords with time magic and magic sword, meaning in boss battles she can go quick > hastega > flare sword on the first turn and then quick > attack > attack after that for huge damage. Once again it's the same effect as the flowchart gamefaqs magic sword/x-fight combo, except better because you get access to actual magic just like Bartz with his katanas.

Now on to Lenna! Lenna is my favorite character to use in this game because of the class I made up for her. In the first half of the game I just have her switching between white mage and summoner. Kind of boring, but standard and she isn't really able to reach her true potential. But summons aren't all that great for this part of the game so she really doesn't have too much better to be doing than healing. Halfway through the game that all changes. When she leaves and then returns to the party, switch her to dancer with summon secondary. She won't be healing anymore. The summon/dance combo is insanely powerful and the abilities have incredible synergy with each other. The way dance works is that each time you select it, it randomly does one of 4 dances. The two best ones will either absorb MP or deal 4x damage. So you can burn MP on expensive summons, then dance and make it all back while also shelling out big damage. There's dancer equipment you can give her a little later that increases the odds of these dances happening. She turns into a complete force. To provide a little more info, one of the big reasons why having your summoner and healer as the same character in the second half of the game is a bad idea is due to the Golem summon. This summon blocks all physical damage to the party for a certain total amount and is hugely important in surviving tougher boss battles. You never want to have to decide between having to recast Golem and having to heal, you want to be able to do both on the same turn. But yeah, even if you take no other advice from this comment, definitely check out summoner/dancer.

I find Galuf to be the perfect jack-of-all-trades for a number of reasons. My first step is to start him as a monk and get brawl, a crucial ability that perfectly fits Galuf. It allows him to use any job while still being able to beat the crap out of enemies. Red mage is the best class to move to after this. A barehanded red mage is probably the most useful character for the first half of the game: you get access to all white and black magic available for the time as well as the ability to switch between no weapon and the heal staff mid-combat to be able to attack for big damage or MP-less healing. Two other jobs I highly recommend mastering at this time are Geomancer and Bard. On their own they aren't too powerful, but with either brawl or red magic secondary they can be just as useful in battle as those original classes, while also giving you extremely useful situational abilities in the form of terrain and sing. Sing is a great secondary ability later on for buffing the party, and the Requiem song is essential for areas with undead enemies, as it does big group damage to all undead. The Geomancer's abilities are also extremely useful in some dungeons for avoiding trap or damage floors. You'll definitely be glad you mastered it early.

Now all these jobs are perfect for Galuf because halfway through the game he goes through a bit of a...transformation that's going to make things change a bit. You'll see what I mean. Well serendipitously, this is also right around the point where black and white spells that can no longer be used by the red mage become available. This is also right around the point that Lenna's going to stop being your healer. You can start "Galuf" over at white mage with a utility ability like Sing as your secondary for now, then once you get white leveled up to where you can use all the best available white spells, switch to black mage with white secondary and level that up. You'll end up with a new and improved red mage who no longer needs to physically attack (brawl becomes underpowered in the second half of the game anyway compared to what Bartz and Faris will be able to do). Late-game you'll also want to pick up the Mime class for "Galuf," as it will let you equip 3 abilities and is ideal for magic users. Black/white/sing is a good combo, but you can also grind out the big amount of 999 AP needed to master the final level of red mage, which will let you go black/white/dualcast. Being able to cast 2 spells per turn is really awesome.

All in all that's a pretty tried and true strategy I've developed that allows your party to synergize well with each other over the entire duration of the game, have all major available bases covered (you could also have Galuf master chemist but I feel it's not all that necessary), and just generally do awesome shit. Hopefully you can pick out a bunch of stuff from in there to incorporate into your own game.