Did anyone ever read the Animorphs books? The group of kids who fight Yeerk aliens (along with other aliens) while their ability to change into other animals. I haven't read these books in a few years, but I used to love them. They aren't very long books, but they are very good and kept me interested. First person is my favorite point of view to read a story in, and they were all in first person.
Well they aren't the small green people we often hear of, the one that gets the story moving is an Andalite (yay google for jogging my memory XD) that's in distress. They all have various circumstances, hatreds, alliances etc if i remember correctly so its not just a re-hash of the green ones. But the one species that i like the best (mainly for it's name) is the Hork-bajir. Yes green and scaly but they look much different.