ok this gets a bit complicated so bear with me.
firstly I am a guy (I believe that was the qualification)
u should try ur best to just be regular, tznius also means not standing out in anyway so if people will look upon u because ur too tznius then u kind of missed the whole point.
second its a hard call with guys some guys find some things attractive others find other things. hair down or hair up most of the time wont make so much of a difference unless ur hair is flamboyantly displayed or very obviously untzinus like the very long shaitels or the hair only covering one eye (sorry if I offended anyone but facts are facts)
I know in regards to dating that many guys (and I’m not from a particularly yeshivish circle Im pretty much avg. I know its relative but I have friends from almost every yeshiva in bk and many in isreal ie: mir, torah temmiah, chofetz chaim, and brisk so I covered my bases) will automatically say no to a girl who is a “puller” or a girl who while sitting needs to consistently pull her skirt so that it covers her knees, that’s a no no. period. again not for everyone but for many guys.
also when picking clothing make sure the color isn’t a flamboyant color, I don’t mean u should wear black and dark grey but use ur saichol, don’t wear a bright red or bright orange shirt and wonder why people are looking and/or saying its not tzinuis. im not bashing anyone who does, rather just answering the question u posed regarding urself.
I don’t know what else to tell u ur question was pretty general but the main point is don’t stand out either way just blend in and ull know ur fine. (obviously stand out if everyone around u is very immodestly dressed).
I feel its inappropriate to go into other factors regarding the way women dress (bec I am a guy) so ill stop here but I must say its very impressive that ur willing to take measures to be more tznius its something people don’t really do today and from what I hear its the hardest nisoyon that women have so good for u!
good luck!