:salamext:
sis, try it - whenever you see any sister - just go for it, smile at her in the face - even if you think she wont smile back (then you can divert your eyes away if you feel shy, but it breaks down a mental barrier and people see you as good.) its sunnah and theres reward in that insha Allah. i used to be shy to do that but now i even do it if i see a brother going by while i'm in the car.. because a smile is free but it gives so much benefit to others.
at the beginning you might feel shy, but this builds your confidence and its nothing to be shy about either - people just start thinking your a good person. the companions would say they never saw anyone smiling as much as the Messenger of Allah (sal Allahu alaihi wasalam). i think it's kool and the smile beautifies people, so your connection with Allah should allow you to be confident because you know you're doing it for His pleasure, so He won't forsake you.
smiling is easier than approaching other people, and that is sufficient for people to know you're not arrogant. because an arrogant person (supposedly) doesn't make the first move. you can do it with your friends, other muslims are your friends too - so work on it from there.. from sisters your close to, to other sisters you dont know..
sometimes the only problem is that some people have faces in which their expression looks slightly grumpy or serious, but by smiling more often - or atleast abit more than before, - people start realising you're a good, flexed out and relaxed person..
pray to Allah to support you.. even in small matters like these. Allah azawajal wil help u follow the sunnah!