Once you’ve defined your overall vision for the community, you’ll want to establish a few clear, measurable goals in order to track your success. If your vision is to reduce support costs, what percentage do you need to reduce them by, and how fast do you need to realize those savings? If your goal is to increase the number of leads in your pipeline, or the quality of those leads, be sure to tie community participation to the customer’s record in your CRM, and incorporate it into the overall lead score.
Make note of your current numbers, and track your progress weekly, monthly, and quarterly against those benchmarks. Once you have a history of results you can calculate the initial ROI, and continue to iterate on that number over the lifetime of your community.