If you don't know how to solve a problem, it might help to put yourself in the shoes of a company or person that you know well, or that has a very opinionated approach to solving problems. Often these brands and people are so famous for their decisions that we have a good sense for how they would solve our problem if they were us.
When faced with a problem, try to imagine that you were another company or person, and how that problem would be solved.
Inez has started to design a new web app that will help people format and edit their photos online. She's got a good sense of what the software should be able to do, but isn't sure what layout or visual design style she should use.
She stops and asks herself: "How would Apple design a photo editing web app?". She imagines this for a few minutes and makes some quick decisions about the style and layout: The controls should be pushed to the outside edges of the interface, and the content should be as large as possible, front and centre. The interface should be monochrome as much as possible to let the photos shine on their own, and avoid distraction.
With a direction set, she feels much more comfortable about starting the interface sketches she needs to work on.