1. Sleep: There's actually science to support this one. Eight hours of sleep helps you reboot your brain, lets you think more clearly and be more creative. Lack of sleep makes it difficult to make connections and even the easy stuff becomes difficult.
2. Eat: Eat healthy foods. Eat a variety of foods. Watch how much alcohol and caffeine you drink. This will keep you well. It's hard to be creative if you get every cold and flu that comes your way.
3. Exercise: Now, I'm not saying that you need to join a gym or get to Joe Piscopo size to prevent writer's block. I am saying that you need to move every day and get your heart pumping. Take a walk, play some basketball or toss a tennis ball for your dog.
4. Read: If you want to write, you should read constantly. There are few pleasures as great for a writer as finding a great book to read. After you have read something great, reread it and absorb its secrets. Then use them.
5. Keep Learning: Take a class, go to a museum, read a trade magazine for an industry you know nothing about or watch a documentary. Just keep learning, the world is huge and the minute it starts to feel tiny, there won't seem like there's much to write about.
6. Write Every Day: Even if it's only 15 minutes a day, write every day. Develop a pattern, a rhythm, that can't be broken. If you write every day, it will become as effortless and necessary as breathing. Better to write for a short period every day than a longer period on one day.
7. Listen to People Talk: Don't just lecture people or tell people stories, listen to what they have to say. These are your characters, your inspiration and the unknowing victims you will steal from. If you really listen to people, they tell you way more than they think. Ask people questions and listen to the answers. Retelling someone's story in your own voice is a lot easier than making something up from scratch.
8. Lower your Standards: As Tony from Bagelprov quoted poet William Stafford in a recent comment as saying, "I believe that the so-called 'writing block' is a product of some kind of disproportion between your standards and your performance ... One should lower his standards until there is no felt threshold to go over in writing. It's easy to write. You just shouldn't have standards that inhibit you from writing."
9. Get Rid of the Doubters in your Life: You know those people you have known forever that don't think you're really a writer and that you're wasting your time? Either learn to ignore them or get rid of them. Dump them. It doesn't matter how long you've know them. You already have enough doubt in your head without having to put up with some jackass adding more doubt outside your head.