I need help

All Ты need to wear is a large рубашка that covers your panties. Thats it :P
....By that I mean Ты can wear anything and it wouldn't matter much ;P Wear what feels comfortable.

it might be hard and difficult,

Here's your solution.

Just dress casually. Some jeans and a red или розовый shirt. Don't stress over it. If you're calm, you'll have a good time.

One thing Ты don't wanna do is dress half naked.
Don't have Ты boobs all out and crap.
Wear what ever is comfortable but classy, ya know.

wear a вверх hat, monocle, cane, just kidding just kidding

wear whatever Ты feel comfortable in, don't stress over it, if Ты wear something uncomfortable you'll be too busy trying to get comfortable that Ты won't be able to talk to him! If Ты want some real ideas maybe ask some other people that are going what they're wearing?