If you find yourself strapped for storage space, then you're going to have to start deleting stuff to make room. Games will net you the biggest gains in storage, so you might want to target ones you haven't played in a while. The good thing about this is that you can always reinstall the deleted game if you want to play it again.
In addition, you can also delete any apps that you don't use. That said, deleting these apps won't reclaim much storage space. Furthermore, you can delete your screenshots and gameplay footage.