The Revenge of the Cheerleaders by Janette Rallison
This is a companion novel to All's Fair in Love, War, and High, School. Both books make sense by themselves, so even though All's Fair is the first book, you don't have to read it first for either story to make sense. Revenge of the Cheerleaders is a pretty normal teenage girl book, and talks about pretty normal teenage things (boys, cheerleaders, popularity, and family). The main characters don't do anything bad and don't like drinking/drugs/etc., but the book does talk about other teenagers drinking at parties. It's kind of funny, and I liked it more than the first book.
Chelsea's year just went from bad to worse. Chelsea's boyfriend Mike just broke up with her and started dating another girl. Her sister's (Adrian's) boyfriend Rick embarrassed Chelsea and the other cheerleaders at the assembly. And then Rick debuted his album all about how dumb Chelsea and her cheerleading friends are. Chelsea and her cheerleading friends are out for revenge, and are determined to get back at Rick. But then Chelsea meets the perfect boy, who just happens to be Rick's older brother. Chelsea must decide what matters most in her life - taking revenge on Rick or her relationships with her sister and Tanner.