[GeeTwo]

As with any engineering project, begin with requirements. In this case, your requirements begin with the rule book. Then, after you've broken down the scoring and identified opportunities and challenges, list your strategic requirements. Prioritize the requirements.
NOW brainstorm designs. Usual brainstorm rules - build ideas up, but don't tear them down yet. Somebody must be in charge of notes!
Select a few basic designs to draw up - more detailed than a napkin, but not a full-detail CAD. Don't pick these by popular vote, but by whether anyone (or a small group) is willing to champion them and do the rough design. We usually have some hand-drawn and some in power point; we've even had some executed in such media as dry-erase and cardboard. As a group, review and rank them according to cost/benefit/risk for meeting the requirements. Look at the likely contenders and see if any of them can be improved prior to prototype. Pick one or two designs to prototype.

If you're ten days in and aren't down to one or at most two designs, you're going too slowly. If you've picked one on kickoff day or the day after, you're going too quickly - either you didn't analyze the game well enough or you haven't slept. The sweet spot is somewhere in between these two, and we haven't quite found it yet; too slow our first three years, too fast this year.