you have to unlock the different classes for each character by levelling up jobs via job points, which are independent from character levels, which are gained via exp points (and are also not especially important imo). everyone starts with squire and chemist as the default classes.
levelling squire unlocks phsyical classes and levelling chemist unlocks magic classes
(boy characters have a physical bonus and girl characters have a magic bonus. we’re claiming ramza as a Child Of Gender bc he gets both. boys who level magic classes can become bards and girls who learn physical classes can become dancers, tho)
each character has 5 skill slots, 1 is occupied by the current job. 2 lets you equip the skills of another class. 3 is an automatic reaction skill to attacks. 4 is a passive skill, and 5 is a movement skill
some of my fav skills per early game classes:
potions and phoenix down from chemist, autopotion and throw item are great too (the chemist class can by default throw items but the only way to get other classes to throw items beyond the immediate 4 squares around them is by equipping throw item). autopotion is a reaction skill that triggers when a character is damaged a % of the time that is equal to the character’s brave stat (it consumes 1 of the lowest level potion you have in the inventory so this is something worth being aware of!)
(chemists can also get guns around the middle of the game, which are really strong)
accumulate from the generic squire class is cool and also a great way to grind job points (you can have characters spam it at no cost) not my fav class out there but ramza has a special squire class that learns some unique very good skills that become available each chapter (in chapter 2 he can learn a skill that has a 100% chance to permanently boost brave stats of who it’s cast on i think). job points up is a great skill too it makes developing characters a little faster (specifically it gives a 1.2x bonus to job points)
knights have really strong skills that allow them to break enemy equipment and debuff (an example would be hitting a boss enemy with “break speed” so many times that their turn economy is completely ruined (this was how i beat queklain / cuchulainn at level 1!)) their range is based on the range of the weapon they currently have equipped. so you can give knight skills to an archer for example and have them shoot weapons out of hands from across the map
archers have concentrate which is a good skill (makes skills such as “break weapon” have a higher hit chance and gives 100% hit chance to most attacks) and are the only class that can equip longbows, which are quite good
thieves learn steal heart which is a great skill for damaging the enemy’s turn economy by making them waste turns, in addition to stealing. anything that boosts your team’s turn economy or damages the enemy’s is especially good in fft.
(some ways to attack the enemy’s turn economy would include but are not limited to: outright killing enemies, giving them status ailments such as frog, sleep, charm, slow, or stop, or the break speed debuff)
for monks, chakra is a great heal / mp restore skill and it’s free! their base attacks also hit incredibly hard and scale remarkably well with accumulate from the squire class and higher brave stats
on the chemist side of things, wizard spells are really strong in terms of damage (especially with element boosting rods) and they can also learn frog which is a Great skill imho
also time mages learn haste which is such a good skill it’s worth casting on all your units all the time (it’s the easiest way to strengthen your team’s turn economy probably) imho. (also they can learn teleport which a movement skill that replaces your default move with teleportation! but that’s a more mid-later game skill)
like many 90s games it’s a little opaque in its systems but you can press the select button to get some tooltips and ui hints here and there. not really the kind of thing only 13 year olds enjoy as its continued popularity with adults on this webforum might suggest
sometime in chapter 2 the character agrias from the first battle joins your party permanently and she’s extremely overpowered (she has many of the same skills as cid, who joins near the end of the game, who is even more powerful)
the stores in each town have different equipment from each other. some have heavy armor for knight / samurai / dragoon classes, for example.
also everything might have a different name depending on which version of the game youre playing
here’s a classic gamefaq that explains basically All Of The Mechanics And Numbers in the entire game:
https://gamefaqs.gamespot.com/ps/197339-final-fantasy-tactics/faqs/3876
(it might also be worthwhile to look up in here how the clock system and the evade system work)
if your units lose all their hp they become unconscious and a 3 turn countdown starts after which they die permamently, which is such a bad outcome it’s worth reloading a save usually, it’s much easier to keep your guys alive than in fire emblem for example tho. the phoenix down skill has a 100% chance to revive unconscious characters and casts instantly, which is not true of the priest / white mage class life ability (items are my go-to for healing usually fwiw)