@Luminox
If you are having that much trouble, you should consider leveling up some between story areas. ALL my characters usually level 3-4 times between storyline areas, and I never need to use quickenings, as they serve little purpose to me other than MP gain for magic users, or difficult bosses. Never ignore Bravery, Faith, Haste, Float, Protect, and Shell. Also, the 'support storm' is good on long stages, which has each member of your party casting either protectga, shellga, or float.
It's good to make sure your weapons, armors, and magicks are updated whenever shops are updated during the game, too. Good weapons are a real advantage, and it shows. Keep in mind that there are combo rates and disadvantages/advantages to every weapon. Weapon choice is very VERY important:
One-handed swords - only above average power, but allows you to use a shield and has a nice combo rate, although slightly on the slow side; Durandal isn't all that strong, but I consider it the best single handed weapon
Two-handed swords - very strong, and actually faster than most single handed weapons, but you lose evasion with no shield; Tournesol and Excalibur are two of the 4 'super' weapons in the game, both having very high attack
Daggers - fastest weapons with an average combo rate and allows the use of a shield, but has pretty low attack; Danjuro isn't worth getting as it's not very strong and difficult to get, but the Main Gauche is one of the most used weapons in the game, having the highest evasion of any weapon; with a good shield and the Main Gauche, it's near impossible to be hit with physical attacks
Ninja Swords - fast and a high combo rate, but you can't use a shield and they aren't very strong; all ninja swords are shadow elemental, so they are pretty useless in most areas because of the undead; Yagyu Darkblade is a very fast weapon with a high combo rate, but it's still shadow elemental
Katanas - average attack and you can't lose a shield, but high combo rates and are pretty fast; while the Masamune has an average attack, it has a 40% chance to combo (the highest in game), and is one of the 4 'super' weapons in the game
Axes/Hammers - based almost entirely on luck, they can hit extremely high damage or extremely low, and allow the use of shields; the Scorpion Tail isn't worth getting, as it is easily outclasses by other weapons
Spears - strong, fairly quick, average combo rate, you can't go wrong with these; the Zodiac Spear is the strongest weapon in the game and one of the 4 'super' weapons, but the easiest to miss if you don't know how to get it, and chances are you've already screwed up
(long-range weapons and measures don't have combo rates, but have a critical hit %)
Bows - in my opinion, the best long range weapon; fair damage, nice range, average attack rate; the Sagittarius bow is by far the best long-range weapon
Crossbows - not much experience in these other than I think they have longer range than bows, but less attack power and they rarely miss; Gastophetes is just the strongest crossbow, with nothing special
Guns - the SLOWEST weapons and low attack, but ignores defense and is 100% accurate, and not dependant on any stats other than Attack; Fomalhaut is the easiest final weapon to get, and it's not that bad, but still slow
Hand-Bombs - comparable to axes and hammers, being based on luck for damage, but are long ranged and you can't use a shield; Volcano has some good damage, but still random damage
Measures - low attack, average attack speed, and almost no combo rate, but they ignore defense and allow the use of shields; adds positive status effects to the target, which is pointless in attacking monsters, so don't bother with these weapons unless you want quick ways of adding status effects without MP
Poles - they tend to be overlooked, but they have a fairly high attack and attack speed, and have a fair combo rate; all poles are based on the opponent's magic resist rather than defense, and the best weapon against slimes; the Whale Whisker is a pretty strong weapon with a nice combo rate
Maces - good for magic users that aren't constantly casting magic, as it's power is based entirely on your magic stat, and allows the use of a shield, but not very strong; the Grand Mace is only an above average weapon, but still good for magic users
Rods - poor attack, no combos, and fairly slow, but you shouldn't be attacking with these anyways; raises MP and slightly raises magic; the Rod of Faith is a great magic weapon because it adds 35 MP (that's +105 with all 3 quickenings) and +3 magic and if you hit a target with it you might add the 'faith' status
Staves - poor attack and slow like rods, but gives the most to your magic stat and raises elemental damage depending on which staff you equip; the Staff of the Magi adds a whooping +8 to your magic stat, and increases holy elemental damage
TIP: You should get Vaan to at least lvl 10-15 at the beginning of the game solo. When other characters join, they usually take the average level of the party, add 1-3 levels, and that's theirs. Like, when Balthier and Fran first join, if Vaan is level 15, they will be around 17-18. It saves alot of time early on from having to train many people at once.