I absolutely love thinking about this stuff. I regularly change the outfits of my comic characters, to help convey the passage of time as well as based on what's practical to their current situation. It's always fun to come up with new outfits for them that keep consistent with their general fashion sense.
Rowan
Main colors: Purples, browns, gold accents
Staple clothing aspects: Scarf, gloves or bandages covering his hands, prefers short sleeved or sleeveless clothing, concealed weapon
Rowan's first outfit is meant to somewhat resemble “normal” clothes as he's meant to not look like a combatant until he draws the dagger worn on the back of his belt hidden under his coat.
His second outfit is after a 6 month time skip, so it's summer now and the outfit gets a bit lighter to compensate for warmer weather.
In more casual situations he goes down to the most basic elements of his clothing, generally a sleeveless black top and pants.
Bree:
Main colors: Blues, black, silver and teal accents
Staple clothing aspects: Her jewelry and holy symbol choker, general pirate-y look, tall boots, teal sash
Bree has probably the boldest sense of fashion of the trio. Her initial outfit is her in her pirate captain uniform.
After the timeskip, she too has switched over to lighter clothing, still keeping important aspects like the choker she wears her holy symbol on.
Her casual clothing is actually pretty similar to the rest of her outfits, as she already doesn't tend to wear much in the way of armor.
Raul:
Main colors: Reds, black, gold accents
Staple clothing aspects: Always wears gloves, roguish leather armor with something that can be made into a hood
Raul favors darker colors as one might expect from a rogue. He's got a belt to wear his daggers on as well as a cowl neck on his top that can be pulled up into a hood.
After the timeskip he's switched to a sleeveless outfit with a hooded cape and a slightly different dagger belt.
His casual outfit features a sleeveless version of the original cowl neck top, and with his armor and weapons removed (but still wearing the gloves).
I'm already working on the designs for their new combat gear for when they venture out again in my next story arc. I find having to draw their outfits over and over for the comic helps me learn a lot which clothing designs or details are too complicated or annoying to have to draw repeatedly, and adjust my fashion design accordingly for the next sets. ^_^