I would say the first thing you should do is just play with it as it came out of the box for a few days or even a week. Take the time to learn where everything is in the OS before you start modding it. Go through all the settings menus and get comfortable with all the stock features first. Doing this will give you a better understanding of the OS and will prevent the overload of learning a new OS plus learning how to mod the OS all at once. Start going through the sticky threads up top first, they will cover a lot of the basics and show you what apps you need first to have all the basic functions of the phone. After you've got that down, then you can look into rooting and custom ROMs
