For me, I used to shop at urban clothing stores and mostly wear bigger sized jeans with sneakers and t-shirts, but now I wear a lot more fitted jeans and khakis with shoes and button-down shirts - it's not as formal as it sounds, but it's a lot more generic and mature than I used to dress. I'm even looking online at a bass pro shop for clothes as I type this and that's stuff I never used to wear.
I've had suuuuuuuuuper extreme style changes over the years.
In Grade 9 & 10 I dressed extremely formal. Like Victorian formal with flowing skirts, lace, corsets and that sort of thing. It literally looked like I crawled out of another century.
Over the years I've slowly toned down, like now I dress in what has been described to me as "Indie Chic with an 80's twist".
So like ripped skinny fits jeans, leather boots, leather jackets, lots of layering and I have a sh*t ton of scarves and belts. I usually stick to blacks, grays, wines, earth tones(tons of greens, usually sages or olives), beige(I don't like pure white) or muted darker tones.
I still do wear a fair amount of lace but I'm a lot more casual then I once was.
When I was younger I was really scared to show any skin at all, so until I was almost 19 I covered up as much as I could. Then I was ok with wearing anything, now I am trying to get more of a professional style.