I wouldn't wear jeans in HK either, mostly because it sometimes gets very hot and humid. Definitely DO NOT WEAR white sneakers... or sneakers, period. Or visors. It will be extremely sunny during some parts of the day (although HK gets sporadic showers), a lot of women keep small umbrellas in their bags for that reason and also to block out the sun.
HK is pretty conservative so don't wear anything that's too short (like short shorts) or strappy tanks without something over it like a cardy. (i got so many stares when i walked around in a tube top that i actually felt ashamed) if you want to wear shorts, i'd suggest something like bermuda shorts-length with a slimmer fit through the thigh. an A-line knee length skirt with a cardy twinset would be appropriate.
The weather will be so nice that you should wear sundresses if you have any, and carry a light cardigan in your bag. Also useful: a pashmina for when you get into places with strong A/C (basically everywhere). If you don't want to bring one, go to Stanley Market and buy one! I bought mine years ago from there and it was so cheap (HK$198). Don't wear heels that are too high, because some places in HK are steep (especially in Central) and have uneven pavement. Try to wear light colors (white, cream, beige, khaki) for your own sake in the heat!
and i got around wearing sandals just fine. something like a metallic thong sandal or ankle-wrap sandals, or gladiators would be nice.