In my opinion its mainly how you wear it like, if you have confidence your gunna look good, because its like everyone else at your school is wearing it too, but if you carry yourself like you think you look good people are gunna think you look good. =)
Than the other little thing is like you need to accessorize lol, get like a ribbon that matches, and like tie it around your head, wear it with some heels if your allowed, and I'm not sure if you want to look hot or just look more attractive, because if you mean hot than your gunna look like a skank by wearing your skirt oober short and all, but cute just have it a little shorter, and for your shirt you could just pin it so it fits a little better.
Like I wear skirts at my school that aren't really dress code, and my shirts are low because I unfortunately have giant boobs with like a tiny waist ha, but I never get in trouble because I carry myself like I am confident but I'm not like oh look at me and my t*ts and legs, like I look innocent I guess ha and cute. So you probably could get away with it if you carry yourself with confidence but like with a smile and act cute not hot. lol ya I don't know if this helped but I really hope it did, good luck with your uniform. =)
Cute shoes, and jewelry- not too much, though, and always do your hair cute. I had to wear a uniform for six years. Not cool. Now I have to wear one for work, so I just make sure I look decent and throw on a cute necklace or some light eye makeup every now and then.
I don't think uniforms are suppose to be flattering, just carry on wearing them, if you really HAVE to change how it looks, just look at all the other girls posts, making skirt shorter etc, but that's just a bit much for me... its only school, you'll be done with it soon, I'm sure you can wait it out. I doubt anyone really cares since they all look pretty much the same.
Make the skirt as short as possible, wear make-up if you can, style your hair, show off some skin. At the end of the day, school uniforms aren't meant to be hot-they're mean to be ugly. Obvs some girls try to hot in them but those girls just end up looking slutty.
roll the skirt, leave the top button undone, get some pins to put on your blazer. :) at least that's what I do with mine. ;) also try wearing a bright colored tank under the uniform shirt. a lot of these may violate dress code, but that's sort of the point. :)