The other day someone comment that I am known for being "pretty creative". Assuming he wasn't referring to how I make myself appear attractive, I responded that I just know things.
Creativity is not just a "thing". It's a mixture of various aspects. Two of the main ingredients are imagination and knowledge. The more things you know about, the more you can draw from that information/experience the create things.
Do not confuse this for being smart. There are plenty of "smart" people who don't know how to apply it. Knowledge is a reservoir to pull information from. Just because you know what a puzzle is doesn't mean you know how it goes together.
So if you want to expand your creativity go out and learn about things in the world. When you wonder about something, look it up. If you find yourself asking "How do they do that?", ship that little pocket computer and Google that shit. Fill your empty melon with information and think of something interesting to do with it.
If that doesn't work, there is always Bizzaro By Design.