People's styles in fashion are relative to their culture and socialisation e.g. upbringing, where they have lived or who they've lived with, the influences in their lives, books they've read, places they've been to, nature of their job, the level of exposure they have and so forth.
The issue of decency in dressing is not exclusive to religion. Even atheists and agnostics know what's decent and indecent. In some workplaces, you can't wear certain outfits. They spell out the dress code and it's not based on religious beliefs. It's simply office etiquette. Decency is a social phenomenon, not just a religious ethic. It defines actions that conforms to the recognized standard of propriety or what's socially acceptable.
For me, as a Christian, irrespective of what your style is, your dressing and fashion in general, should be based on (1) decency, that is what is decent, (2) dignity, what is dignifying, (3) what is appropriate, with regards to the nature of the occasion, (for example, I shouldn't wear a beach oufit or what I'll wear to the gym to a church service and vice versa), with regards to the weather, (e.g. the misfit of wearing a sweat shirt in the heat, or wearing sleeveless, when it's cold), with regards to your size and body frame and features, (e.g. a big sized person wearing a tight top, with all the vitals uncomfortably protruding, or a slim figure wearing an oversized attire, is awkward), with regards to aesthetics, ( this is not just about what's the fad, but what fits, a lady wearing slim pants should wear a big top, a man shouldn't wear a striped shirt on a striped trousers etc.) and (4) what glorifies God, my dressing should glorify God, just as everything I do should glorify Him. This subscribes to the principle of imago Dei. As an image bearer, what I wear should rep Whose image I bear.
These four factors should undergird a Christian's dress sense.
Now, on 'moderation', we have often quoted and applied Philppians 4:5 wrongly, and we typically use it as a stereotype against women's dressing.
First, the scripture has nothing to do with dressing at all, not to talk women dressing or fashion. You'll need to study the passage in context, especially with reference to verse 2.
The word "moderation" as rendered in the KJV actually means, forbearance, gentleness or a gracious attitude and not modesty in dressing, as wrongly assumed and taught by many. The word describes a person who is really free to let go of his anxieties and all the things that cause him stress, because he knows that the Lord will take up his cause.
Second, if we want to teach modesty, which is a good thing, then we should use appropriate scriptures. Paul and Peter actually touched on modesty in their epistles (1Tim 2:9-10; 1 Pet 3:3-4). However, modesty should not be targeted at women alone, and modesty shouldn't address only dressing. It should touch all aspects of our behavioral disposition, with the propensities for extremes, e.g. eating, drinking, talking, playing, celebrating, entertainment, and so forth.
With particular reference to dressing, it is noteworthy that modesty is relative. The word 'modesty' comes from the Latin word modestus which means "keeping within measure". Standards of modesty are culturally and context-dependent and vary widely. What is modest to Mrs. Alakija may be not be modest to the wife of Apostle Awosanya,
Mrs. Alakija is a billionaire and a philanthropist, so she can afford to wear a jewellery worth 200, 000 naira, a luxury handbag of 20,000 dollars, an Alexander McQueen vintage gown of only God knows the worth, but for 'Mummy' Apostle Awosanya, all that may be immodest, because given her budget, there are other priorities that require attention, which would be scuttled, if she ventures into the league of Alakija
One significant ethic that should define our modesty is contentment. And contentment is usually defined in the context of what we have and can afford at the moment and not what we would have loved to have in comparison to what others have.