Focus: No need to re-invent the wheel if it's not broken! Write down your problem. Draw it. Break it down into steps, parts, and sequences. Think about the minute details and elements creating the experience with the product. Pick the most important element of the problem. Now we're ready to attack it without the distraction of all the other parts.
Example: My toothbrush isn't comfortable. Toothbrush = bristles, head, neck, handle, rubber pads, cover/case, stand, batteries, switch....The toothbrush feels OK in my hand, it's my mouth that's most uncomfortable. The bristles are scratchy.
Shift Your Viewpoint: If you just stare straight at the wall you'll never see the path that goes around it. You have to look at it from another angle. Take out the dictionary. Flip to a random page and point at a word. Take that word and ask yourself, how could my solution be like this word?
Example: Scratchy toothbrush bristles + egg = eggs have layers, yolk inside white, maybe the bristle can be layered, a hard core with a softer outside, firm for pressure yet gentle on the gums!
Pair your Problems: Trying to kill two birds with one stone requires you to find a new kind of stone. Take two elements of your problem and see if one solution will fix them both.
Example: Scratchy toothbrush bristles + inflexible head = if the head were made out of a softer material it could flex more, the bristles could be part of the softer head, maybe the entire toothbrush is a hard core with a soft covering!
Think Backwards: It's often easier to find your way home than to go somewhere new. You know what your problem is. So imagine the ideal experience and trace a path back to the problem.There are many other techniques for thinking "laterally," as opposed to linear thought, which tends to take us down existing paths. To find a great idea you need to jump off the side. Check out Edward DeBono's classic books for detailed info on lateral thinking techniques.
Example: If my toothbrush is comfortable then it fits my mouth, my gum line, my teeth...a piece of gum fits my mouth and teeth...maybe my toothbrush head can squish and conform to fit my mouth just like a piece of gum!