This can start by recognizing common interests: stability in Afghanistan and Iraq (where Iran provided America political support and intelligence in the wake of the invasions); upgraded energy infrastructure and trade in the region; a reduction of Sunni militancy like the Taliban; and a Central Asia and Gulf in which Iran does not feel threatened.
Of course, a resolution to the deeply ingrained differences that drive Iran’s nuclear program won’t happen in a day. Talks are a single event; but diplomacy is a process that takes time and commitment, and engages the multiple power centers in each country.