When creating the appearance of your character that you in some way, please incorporate at least one of all characteristics listed. Now I'm flexible, but for example, Black Mages can't be weighed down by clunky armour, nor do the warriors need to be constricted by layers of robes. If you need to, draw inspiration from costume elements from Final Fantasy Tactics/ Advance, the Dressspheres from FFX-2, or any other class-based Final Fantasies. Depending on where your character originates, those from more humid climates will wear less, and those from the northern climates will tend to wear more.

You my ask 'why should we alter the clothing according to class?'. Good question! Because a person's class is a thing of pride! You'd WANT to show it off and tell the world 'I'm a (class name here)!". So do it!

The Monk, White Mage, Black Mage and Conjurer are grouped with the Master, Devout, Magus, and Summoner. This means that the latter classes mentioned are an upgrade, or advancement for the former.
The first group would only have to incorporate one, maximum two attributes from the list into their appearance. The second group, the advancements, would have more than two, and sometimes all of them. And conjurers and summoners would most likely keep a small momento of when they were in the white mages or black mages, but this is a personal choice.

Note: If colours aren't specifically specified within the descriptions, it can be of any colour.
Note: And this is important - these attributes can be interpreted in any way. Example: A sash doesn't always have to be in one specific place, and there's not always one sort of hat.

Warrior - [Shoulder armour, and various random armour pieces]

Soldier - [Large belts, armor, overcoats]

Monk / Master - [Large boots and gloves, Bound hands, Non-restricting clothing]

Samurai - [Bound/Wrapped undershirt, Open overcoat - long open sleeves, Hakama pants, Helmet and/or bandanna - with 'crescent' moon sometimes inverted, Plated armour - chest protector and arm/leg layered squares or rectangles]

Dragoon - [Dragon-themed armour, Larger armguards and Boots, Partial or full capes]

Thief - [Bandanna or headband, Short-sleeved collared shirts, short-legged pants or shorts, Sandals, Large Belts]

Ninja - [Masked faces, Bandanna or helmet, various pouches for equipment, tight clothing - yet not too constricting]

Archer - [Chest protector (either for entire chest or half of it), gloves with reinforced inner panels, Wrist supports, Quiver]

White Mage / Devout - [Red triangle trim on white combination, hood on head (older mages usually have their heads uncovered), Wooden or wood-shaped staff or rod, Cat ear hood (more common with children)]

Black Mage / Magus - [Wide brimmed pointed hat, golden sheen over eyes, anything striped with two colours, large gloves]

Time/Space - [Large red pointed hat, Star symbol or pattern, hem patterns, white and dark purple to light blue robes.]

Arcane Mage - [Large hooded cloak, jeweled forehead adornment, large patterned belt, light inner robes, wrist gauntlets or jewelry, neck wrapping.]

Green Mage - [Green (and sometimes Orange) cloak or robes - usually short, Large boots, Finger rings, Any sort of hat or head covering, Wrist bracer]

Conjurer / Summoner - ['Horn' headband; Patterned/Embroidered Robes; Blue, Green or Yellow incorporated (the most common of these are green trimmed with yellow); Criss-cross binding; Large, belled sleeves]

Blue Mage - [Mostly blue clothing, A (domino) mask, White feather on a blue hat (or somewhere around the head)]

Geomancer - [Patterned robes of 3 or more colours, 3/4 or 1/2 length robes (to allow movement between terrain), Moderately sized gloves]

Trainer - [Orange to red robes (accent colours are open though); Overcoat, clasped in front of chest; some sort of headdress; sheep skin or horns]

Paladin - [White clothing and armour with accents of gray or gold, Similar armour to the warrior however just more of it.]

Dark Knight - [Darkened, almost black armour; armour becomes ridged, even with points; Similarly themed helmet or headgear]

Red Mage - [Light red to dark red cape or robe - usually multi-layered - lined with yellow or gold; light red to dark red hat - large brimmed but not pointed; yellow or gold feather around the head or hat; Boots]

Alchemist - [Apron, Large bag and smaller pouches, long sleeved shirt underneath a short sleeved jacket or shirt, some sort of head covering]

Bard - [ Lightweight Tunics, Feather hats, Bandana, 1/2 or 2/3 length cloak/cape (sometimes patterned with bright colours]

Dancer - [ Revealing in general - non-constricting and sometimes skin-tight. Accents like frills or metal are added in various ways, it depends from dancer-to-dancer. It is hard to determine since each Dancer is different.]

Mystic Knight - [ Clothing similar to middle eastern attire: bandanas, wide pants, and lower-face masks. More gender-specific though; turbans for men, and more revealing, belly-dancing attire for women.]

Machinist - ['Apron' slacked from the waist - usually around only one side, long capes, belts with numerous pockets]

Mimic - [Any sort of full-faced mask, Large boots]