There is really no easier way to freshen up your homescreen then to add a custom wallpaper. The folks over at AndroidGuys put out some pretty great wallpapers on a regular basis. They have most recently released a series of 20 water themed wallpapers. They also have a Google+ page where they release wallpapers all the time. Simply download the image and set it as your wallpaper. Grab these and many other wallpapers at the source link below!