Hello! In the past iv been a professional concept artist and one of my fave parts was always designing clothes and shoes for characters haha. The advice i have is to first of all start with what your character does (i know this is your persona, so think about what you do or would like to do) or what activities they get up to, i find that a good way to make an interesting and storied outfit is to incorporate unique aspects that allude to their interests or hobbies. Think about stuff like:
- what does my character do in this outfit?
- does the outfit lend itself to that particular activity, is it practical for that purpose?
- what do they like about the outfit, would they customize it?
- how long have they owned it, would it have signs of wear?
- what about their personality drew them toward this outfit in particular, can you express that in the design?
to illustrate my process for how i make character costumes, here is one i made a long time ago for an example:

The concept for them is that theyre into fashion, prefer to live stress free and enjoy themself but they also need medical attention frequently. As you can see i opted to blend their fashion sense with hospital inspired elements:
- the light blue jumpsuit evokes medical scrubs, but the slit shoulders and straps on it make it kind of impractical for that purpose which imply its more for fashion than practical use
- they keep a hospital tag on their wrist as an accessory
- medical adhesives/tape, perhaps where they had a catheter recently or maybe they just like the look.
Then i also wanted to both flavour their outfit with their chilled out vibe, but also incorperate some contrasting colours to make it interesting. most of their outfit is fairly plain so far so i took this opportunity to add some visually "noisier" elements:
- Brightly coloured rainbow designs on their shoes (this is a super easy way to add a lot of colour quickly btw) as well as clouds because they're pretty calming and fit naturally with the rest of the theme and colours
- the chunky socks also give off a cloud vibe for me
- Bubble/boba tea themed bag accessory, gives off chilled out vibes (or at least thats how i associate bubble tea haha) it also mirrors some colours/design elements from their shoes to balance out the overall design. if you look closely you can also see they carry some medication in their bag, which again reinforces the healthcare theme
- some cool fashionable glasses, kind of goes with he summer-y vibe they ended up with and also just for another opportunity to use that orange colour again
and finally, their wings and halo were already going to be part of the design but i took the chance to consider how they could complement this character in particular:
- their wings are cartoonish and soft with cute swirls
- their halo is cloud-like
Finally i just wanna go back to their bag, it is a highly unique item for this character and unmistakably belongs to them, you can see theyve even personalized it with some other little trinkets (capsule keychain, tamagotchi) so it definitely expresses a lot about them. take the time to consider not only what you character wears, but how they wear it. really i think the best question to ask yourself is
"what does this outfit say about my character?"
, it doesnt have to be anywhere near as complex as what i have going on, you can think about this stuff to your own taste/comfort level, but i encourage you to give it a bit of thought at least. Even the cut of a shirt, some pin buttons on their bag or some jewellery can go a long way.
You say you want your character to have a few different outfits, depending on how different you want all of those to be you may have to do this process multiple times. I think its possible to get creative and see if you can spin the same design in slightly different ways to convey the same or similar message, this also has the benefit of giving your character's wardrobe a sense of cohesion.
Anyway, hope this helped a lil bit, if youd like i can give you some constructive criticism and tips on what you have so far, ur welcome to dm me about that, feel free to ask questions too