1. Get an antivirus app like Avast or AVG
2. Get a battery life management app to improve battery life. Juice defender is pretty good.
3. Sync contacts, email, etc. through Google
4. Transfer music from PC through Google Play manager. All music will be available on current and future android phones.
5. Change the launcher if you really want to customize the look of the launcher. I suggest Nova Launcher since you can change icons.
6. Get Zedge app for wallpapers, ringtones & notifications