If you were me, I would read A Song of Ice and Fire first, Lord of the Flies second, To Kill a Mocking Bird last.
I've been wanting to read asoiaf for ages, but my mom never let me.
I'm not a fan of lotf, but it's school work and that's that. (I just envy the people who get to read books as their homework. Even if it's classic literature, and those tend to be less interesting)
I might have read tkamb before, I can't remember. I'm not into depressing books, so I'll always read that last.