Set aside time to daydream. Kids have wildly fertile imaginations and spend much of their time playing make-believe in one form or another. Daydreaming is a way to tap into that childlike spirit and just let your mind wander from topic to topic, with no restrictions, just a gentle push in the direction of "what if."
Surround yourself with inspiration. Pictures on the wall, books on your shelf or--better yet--open on a table, photographs in frames or even a big window with a great view (if you're so lucky to have one) can be a tremendous source of ideas and help you get into a creative mindset.
Tour an art gallery or museum whenever possible. It's been said that art is never truly finished, that it's always changing even by someone taking a new look at it and offering his own perspective or impression of it. Really look at the art of others: brush strokes, camera angles, stitch and weave patterns. The fundamentals of a craft can jump-start your mind into thinking of your own ways to use those building blocks.
Color in a coloring book, sculpt with kid's clay or put together a model or toy. These tasks are often simple and quickly done, but they allow you to feel a sense of accomplishment while hitting the pause button on your active thoughts, letting the more creative, random ideas float to the surface.
Look at nature and try to envision it recreated in a different medium. My favorite is to look at flowers and think about how they can be reproduced or transformed into beaded pieces, either as jewelry or mini sculptures. Once you start equating tree bark with fabric or clouds with spun sugar, your mind will start to skip around and branch out to other possibilities.
Write everything down. Even the tiniest idea that you have in passing should be recorded in a notebook. On days when nothing else comes to mind, flip through those notes and pull one out to work on.
Keep multiple projects going at once. The key here isn't to split your focus. but to give yourself many possibilities whenever you want to work on something. It does help if you finish one every now and then, but the concentration, at least in general, should be on the creating, not the end result.