"But Tyran-sama," you ask, "you've told me how to level, but where do I get the equipment to fight these mobs?"

The answer is fairly simple. At earlier levels, you can simply use Kaipo equipment (get to Mist in the FF4 world and go to Kaipo from there), which is cheap and fairly good. Once you get to Imperial, some of the equipment you can buy in Tzen works well, but bear in mind some of that has a level requirement.

A sample Fighter equipment set at roughly level 15 looks like this (I'm assuming low income):
Decrepit Old Sword or the Relidia sword
Shell Shield
Bejeweled Helmet
Chain Vest
some random Pravoka accessories

A high-income Fighter set at the same level looks almost the same but has Armored Boots, which are amazing accessories that are usable at any level because they give battle_speed_up.

Black Belts are easy to equip, just get some accessories and the Kaipo suit and you're set. Palm Handclaw from Kaipo will fit for a while to come.

In general, for weapons you shouldn't be putting heavy priority in base power yet (truth be told, few weapons even break 150), since until third-tier classes, pretty much, damage is dealt with magic or Suplex.

Armor is trickier. You can go for high-defense armor only, and that does work at low levels, but at higher levels when mobs start hitting you for ridiculous damage anyways, you want to put stats over defense.

Accessories at low levels mostly give small defense bonuses, but when you get higher you'll be using them for status mods and elemental resistances. Basically, if you know the mob you're fighting always casts, say, Blaze, then having a Guardian Armlet equipped can help a lot more than something that gives 10 def.

Mages work differently than fighters, obviously. You don't want to put massive defense over stats ever. What you want in general is a stat called "m_power_up", which obviously increases your magic power. The Mysterious Blue Robe from Pravoka, or the Black Robe from Mist are excellent robes that will last you to endgame. The Sleepy Robe from Tule bounty shop is also a fine alternative. For weapons, a Bronze Rod from Tule is sufficient, or an Octagon Rod from Albrook if you're a White Mage. Red And White Leather Gloves (it's one item, not two different sets of gloves) from Nikeah are very powerful mage accessories for any level. Otherwise, battle speed gear is good. Place low priority on defense.

In closing, yes I know that this article was barely informative at all, but c'est la vie. A lot of stuff can't be explained, you simply have to play the game and figure things out on your own.