How to come out with your own magic tricks?  

There doesn't seem to be any new discussions in this topic so I'll start.
I'm just a hobbyist magician (4++ years), so all the tricks that I perform are usually the ones that I learnt from dvds, books & gimmicks. I also mostly do tricks at gatherings & parties for free just for the fun of it (I know some magicians don't like free shows).
So in the back of my mind, I always wished I have something that I can call my own. Something that no one has seen anywhere before, but I don't really know where to start. For gimmicks like I*******e Thread or T***b T*p, I can create my own presentations once I know how to utilize them, but what I would like to know is how to create a new gimmick, a new card trick, etc.
Have you guys created any new tricks? How did you get the inspiration? Please, share.