Ahaaa I love this question and reading how everyone does it! (apologies in advance if I gab a lot here lol)
I highly encourage building moodboards, like you're describing. I have one for each character--and, it's more about the ideas, colors, and vibes that evoke the character and less about exactly what they wear or look like.
Ghosts in the Attic takes place in the mid '90s and with teenagers from different backgrounds (like wealth, ethnicity, location, etc.) I've done a lot of looking into on that era's fashion in my own time, even before I started on the comic. (Also read about '70s fashion, because the '90s are a huge revival of the '70s in a lot of ways.)
My goals were to not to represent aesthetics, but more of their personalities and how that character would even obtain their articles of clothing. One character (Marie Castillo) has 2 older siblings, so I keep it in mind that she has some hand-me-downs. Even though a character (Kevin Anderson) is very goth/metal in appearance, I don't like doing the, "Oooh, let me just look up goth attire and dress him in that." That seems sacrilege, lol. He doesn't have the means to obtain an immaculately gothic wardrobe for himself--and he's not really going for that either. (he also chews on his comfort clothes a lot, so long sleeved things are trashed at their edges.)
The main dude (Parker Wexford) is a skater--baggy, comfortable clothes. His clothes appear ratty because he moves a LOT in them and they get worn out from falling onto concrete. He doesn't have money to buy new and "in" things, so his wardrobe is limited. He's also a silly goose and has some goofy graphic tees he thinks are funny or interesting he's kept over the years.