David, that’s a big question, with enough answers to fill a book (which is why I’m writing one!). Here’s a couple for starters having to do with idea capture:
I’ve mounted a pad of waterproof paper and pencil from Aqua Notes inside the shower so I can write ideas down the moment they occur to me. The reason is that we tend to lose most ideas within 5 to 15 seconds of having them, and why let a little water interfere with a good idea?
Use your phone to dictate notes when you can’t write, draw or type (walking, driving, etc). Evernote has an audio function which can be accessed hands-free in various ways through Siri (with the help of IFTTT or an iOS Contacts hack).
Bottom line: optimizing idea generation is only as good as the ideas you keep.