I randomly remembered a useful creativity exercise which definitely warrants sharing:
Your second to last piece of advice is actually something that's commonly taught in improvisation classes. It's called 'automatic writing' or 'auto reading' and its a very cool technique. What you do is close your eyes and imagine a book on a bookshelf. Describe the bookshelf, describe the books. Take one off the shelf. Describe it in more detail. Now open it. What's the first line say? "It's blurry," the student says. "Here's some glasses," I say. "The words are in a different language," the student says. (They often resist at first.) "You remember that you speak that language," I say. And sooner or later, an incredible thing happens. An intense, intricate and completely original story begins to spill out of them.
I have never tried this with music, but the principal applies. Imagine sitting at your DAW. You open up an amazing song you've never heard before. How do the first four bars go? Whoops, you forgot to turn your imaginary speakers up. Okay, try again. Whoops, wrong file format. It's okay, the DAW opens it anyways. Basically you are trying to access a memory that doesn't exist, so your funny funny brainmeats will actually form a new memory (an original song!) to try to fill in the blanks. All you have to do is listen to it.
Works wonderfully for anything really, and can even be quite fun.