so far, i've been the ranter, so now i'll be constructive.

I'm glad you've got a character arc planned for your brat, i'm glad the point of your novel is her growth and change, but i have to have at least one characteristic in the first few paragraphs to make me care about your character and stick around, rooting for her to grow up and see the good within herself. I have to see those good qualities that she can't see because she's too busy screwing around with her friends. If i had a hint of those characteristics, i'd stick around to see if discovered them herself.

i agree with d. leroy and nom de plume.

basically right now, you've got a girl lying on a beach taking an infodump. it's all an internal monologue of backstory. the action doesn't even begin until the beach drinkers catch her eye. Cut, rearrange. Have her discover the beach drinkers much earlier, all the information before it can be scattered around later through dialogue or flashbacks while she's drinking.

I mean really, what does a teenager love more than complaining to herself? Complaining to other people.