-Some advice that the exceptionally talented Ms. Gruebel has given me, is not to force something if you're not making any progress. It's good advice, because there's definitely been times where I've beaten my head against the wall trying to write a 200 word intro for like five hours. (I call those days "Bad Days.") So, if you're not making any progress solving a particular problem, move on to something else, and come back when you're fresher.
To balance her advice, though, I will say that sometimes it's necessary to muscle through on a project you're just not making progress on. When that happens, my best suggestion would be to stay as relaxed as possible, and keep trying to approach the problem from different angles. I make a lot of pen-and-paper lists when I'm stuck like this, just writing down (stream-of-consciousness-style) anything I can think of. Sometimes it helps me break away from an idea I'm too committed to that's just not working.
-I am a big list advocate and an outline-lover as well, and while I think these organizational structures lend themselves a bit more to writing, I have to say they can be very useful for organizing your thoughts and plans. Sometimes it helps to get things out of your head and map out your plans visually. Think of it like idea-Legos, where you can switch parts around and build whatever you want, except that now it's much harder to choke or build a sweet castle.
-There's some other stuff that I'd like to talk about, like building a good workspace, or how to avoid distractions, but those things are kind of harder to define in 50 words. What I mean is they're very personal aspects of creativity, and I can't really recommend any specific tips. I will say, though, that it helps to be flexible in these areas. Before I came to Promo Marketing, I had to write in total silence. Now, I write with music on pretty much all the time, partly because it helps filter out background noise, it helps me concentrate sometimes.