This was the first guideline that I created for myself to follow, and the one I work hardest at. So the idea is to sketch faster, produce more, and to not stop and think too much about what I was doing when I was starting a design, but to get the ideas out, make them flow, and produce more.
I wanted to start to try to come up with as many ideas as possible for any one problem that I'm trying to solve, because more is really better at this stage than diving deep into details.
Working fast and generating more is fantastic if you're working in a design studio or any size team. Anyone can participate from designers and developers to business analysts and stakeholders. There are several great techniques that work well for eliciting more ideas that you can look to for inspiration. The idea with these techniques is that you gather around a group of people to work on one idea, with each person sketching a number of solutions for a problem.
I like the team-based design concept that I've heard Tod Zaki Warfel discuss. His "6-8-5" exercise works something like this. If each person in a group of 5 people got together and were given 5 minutes to to sketch 6-8 ideas for an interface, at the end of that 5 minutes, you'd have a pool of 30-40 ideas you can review. It's a fantastic idea for rapidly exploring concepts in a team. See the links below for resources to help you incorporate these exercises into your process.