Whatever field you're in, keep a sketchbook with you as much as possible. Any idea you get...any idea at all, jot it down. Save it. Go back to the sketchbook about once a week and see what you've got. It could be that you'll find completely unrelated things click together at that moment and presto!
To be brutally honest, I'll never be able to share some of my best ideas because I never wrote them down. Why? I forgot them. I actually believed that the idea was so great, so powerful, there was no way I could forget it, but when it came time to sit down and get it started I would stare at my canvas blankly...stupidly.
Well, there went that great concept.
On the brighter side, there have been times when I couldn't for the life of me come up with one inspiring thought, but after a quick flip through some old, battered drawing pads I found myself re-energized and ready to go. Keep a sketchbook, that's my big advice for the day. It's easier than a journal (which is also a fantastic plan), and you'll be surprised at the riches you rediscover.