[Illustration attributed to Sean Gallo at http://www.seangallo.com]
How do you approach a large project? (The same way you eat an elephant.)
My mantra is to break it down into smaller parts and methodically work my way through. How you work your way through can vary. If it is something you quickly want feedback on I like to iterate, as with agile project management. If the requirements/goal are more static, waterfall may be the appropriate technique.