Steve Simmons and Ben both make excellent points. Creativity is very "do or do not - there is no try". Learn a wide variety of tricks, expand your knowledge of sleights and solutions, keep on just playing with magic and sooner or later you'll stumble on something.
That's not to say there isn't method to creativity - but its something which you have to learn by feel. Nothing says you have to be creative though! More often than not what you'll end up doing is more personalisation of a trick than something new and revolutionary. Everyone has a preferred toolbox, and so it makes sense to approach a trick using that toolbox. This is a practical, sensible approach to creativity.
But if you insist on wanting to do more, why not start with a trick that you like. Strip it down to the fundamental premise, and figure how you can apply that premise in a different direction. An example from David Stone vol 2 - Ringbox: a ring is borrowed, turns into a key, the key unlocks a small wooden box, and inside is found the ring. What a stunning premise for a trick! The idea that the object turns into something which provides a clue for how to find it again, superb stuff. There's about a million different ways you could apply that idea and come up with some great ideas for tricks. Then its up to you to find a solution.
