First day of school outfit? Help?

k i'm 13 going into 8th grade and i have no idea what to wear! i shop at H&M n roxy mostly. the only jeans i wear are dark and skinny, i wear them pretty tight. i want to look kinda effortless pretty and chic but casual. my style is casual/ sometimes girly. i'm 5'5 and like 110 pounds. what should i wear? all answers are great =) oh and i hate abercrombie and crap like that, i'm not a prep. i'm debating over weather i should wear jeans but it might be a little hot (around 30 degrees, what do u think would it look weird?) thanks =)