Are there rules for this?

There is a code i personally adhere to when and if i go out on dates -

If you're going to the movies, a walk in the park অথবা a picnic ever দিন clothes like jeans শার্ট and sweater will be fine.

If it's a lovely ডিনার for two maybe a cute little dress with pumps and a জ্যাকেট to go over the top.
Any dress will do but i prefer ones with the leg o mutton sleeves link
অথবা an off the shoulder ankle length thing.
I don't really wear high heels, but আপনি can if আপনি want.

Really it's up to you. আপনি can wear whatever the hell আপনি want, it's your date. If আপনি feel pretty in your birthday suit go in your birthday suit, just be prepared to get arrested for streaking halfway through ডিনার though...and be careful with soup...that can be very hot.

Yes, I would most certainly say there is; in fact there's one in particular for all of life & that is: don't wear short অথবা revealing things (e.g short shorts/skirts/tops/dresses, bikinis, low-necked tops, spaghetti-strap top, ect.), because guys are visual & if they see too much of your flesh, then they're going to think of আপনি sexually (not that they won't still like আপনি for your personality, but just try avoid that kinda wardrobe). There's plenty of fashionable modest clothes out there & they're not that hard to find :).