Please help me! Prefer Teenage girl help!?

Okay this guy I like is having a party for summer and invited me. It's this Friday! All of his friends tell me he likes me! I'm only eleven so it's kinda not like a real teenage party. His parents are allowing him to have this party but... they'll be upstairs all night there's gonna be a ton of people there P.S he has like mansion i give this guy hugs and we mess around a lot at school but we always have our friends with us so it's not weird. im mostly tom boy i wear b-ball shorts converse and t's i usually straighten my hair and put a waterfall braid in he told his friends i looked cute on picture day and that was when i was dressed all girly. I have A LOT of girly clothes i usually don't wear them but if he likes me in them then give me some girly ideas to wear. I have blouses dresses skirts pretty much everything and i have and older sister whose clothes i can borrow she's way girly and twelve i have hair down to my armpits and it's a dirty blonde. Please help! Any ideas?