I find that getting something on the screen as soon as possible really helps focus the problem for me. It helps me decide what to work on next. Because if you're just looking at that big to-do list it's like, eh, I don't know which one I should do—does it matter which one I do? But if there's something you can actually look at, even if it's just the debug output of your mailbox parser, it's like, OK, there!
"Coders at Work: Reflections on the Craft of Programming". Book by Peter Seibel, September 16, 2009.