I'm very passionate about creating, this last year I have created a ton more than I have performed. I work with Rick Lax and create much of the magic that you see on his entertainer page. This has lead to some other consultation work with other television. Over the last year I have become, as Jim Steinmeyer would say, "invisible". It has been a blast.
Having so much expected of you and on such a consistent basis I believe it would be unwise not to have some semblance of a process. I have created a process and while I don't always follow it, it has saved me a few times when a deadline looms.
1. Consider Parameters: What can I do, what can't I do? What resources do I have? What is my venue?
You might skip this step but if you do you will miss a framework that can really help in the creative process. If you want a usable effect that you can actually perform than you have to know what you will be able and willing to do to pull it off.
I created a poker chip trick a few years ago. I decided from the begining before I even knew what the props were that I wanted it to happen at eye level and I wanted it to work without a table. Those are parameters.
2. Consider Methods: What methods work given my parameters?
Some magicians prefer to look at effects first, and I admit that I sometimes do this, but I believe that more originality and more volume comes from method first creativity. "Spidey" Akelain claims that magic creators can be split into 2 groups, method first and effect first creators. Jay Sankey is a method first creator. He finds a method he likes and milks it for all it is worth, that's why you get whole DVD's on the bill switch or Paperclipped. It is because he looks at a practical method and asks himself what it can do.
I would consider myself to be a method first magician. I think it is easier to find methods that fit parameters than it is to find effects to fit parameters. There is also the pitfall that many effect first magicians fall into. They start repeating old worn out methods. They fall back on the double lift or a false transfer. The double lift is a great move but it might be unwise to have 15 effects in a routine that all use this same method. I find that method first creating provides more variety.
3. Consider Effects: What types of effects can these methods create?
This is where the clouds part. Effects seem to fall out of the sky when I have a method in mind. Once you get a method in mind go crazy, what could you do with this method? Really brainstorm. Could you replicate an old piece of magic? Could you aproximate a movie effect? Is there a dream effect that this just happens to fit with?(This happens more than you might think). Once you have a method the possibilities start to lay themselves out.
4. Consider Presentation: How can I mesh the method and effect together to be easy to follow and entertaining?
After all of this you have to be able to present this. This might be the hardest step. This might cause you to need to kill your ideas in the previous steps. You might have a killer method that just doesn't work. You may have to lose it and start over to some extent. At this stage, trim away the fat, get some outside advice here. It is less important to get input at the other stages, the presentation part is what makes it entertaining.
So that's my process. Integral to all of this is to always be studying things that inspire you. For me, I am inspired by puzzles, mathematics, science psychology, language, magic, movie making and storytelling. Maybe for you it is something different, imerse yourself in these things and ask yourself what you can create with that knowledge.