What should i wear for this event?

okk so I'm going on this youth retreat next weekend and I really like this guy thats going to and apparently he likes me as well so I wanna dress really cute but not to over the top so I was wondering how I should do my hair/makeup/clothes ect. its in like maryland but the weather will be warm wnough for short sleeves, but cool enough that i should prob ear long pants. and like i think i wanna stay away from skirts or dresses just cuz ill be like walkin around so yeaa, oh and it's for 3 days (friday, Saturday, Sunday) and I'm 16 so please help me out!! and thanks in advance :)