Here are some of the key principles:
Keep the scope as simple as possible. You don’t need to do everything with this project. In fact, if you can just do one thing, that’s perfect. As small a thing as possible. Don’t redesign an entire city—just work on one building. If the project starts to get complex or seem overwhelming, narrow the scope. Do less. It’ll help you get things done.
Practice ‘Good Enough’. Perfectionism is the enemy of completion. Nitpick and worry about getting it “just right”, and you’ll never get it done. Done is better than right. So if you start to nitpick and worry about perfect, say “screw it” and then just try for “good enough”. You can always make it better in the next version.
Kill extra features. Similar to simplifying the scope, you’ll want to try to make your creation do as little as possible. Want it to talk and walk and cook breakfast? Just try for talking. Want your website to publish great content and have social networking and podcasts and news and a newsletter and a membership area? Just shoot for great content. Whenever you find yourself adding new features, see if they can’t be killed.
Make it public, quick. Your goal should be to get your project in some working form out to your customers/readers/public as soon as possible. In as few steps, as quickly, as easily, as simply as possible. Remember: don’t worry about perfect, and don’t let this first public release be wide in scope or full of features. Release it with as few features as possible. Releasing it publicly will 1) get you to done faster and 2) put some pressure on you to make it better, quickly.