A key method I use is to be interested and curious about an eclectic mix of topics. I also capture notes and ideas, web links and readings, as much as I can. That way I can return to that resource and dig for ideas, mine my knowledge.
Here are a couple of other ideas to help you invest in creativity:
Cast Widely – commit to a period of time where you are learning broadly about a topic and the ideas it connects with.
Time for Tangents - take time to meander and explore new paths that you were not expecting. Sometimes the rabbit hole might lead somewhere.
Developmental Learning Space - with a burgeoning amount of information make use of a space to keep those elements of interest and study within our eyeline.
How do you invest in the conditions for creativity?