Fast answer
For a first Martina Franca evening, start around Piazza Roma and Palazzo Ducale so the old town has a clear entry point. Move toward San Martino and Piazza Plebiscito for the strongest baroque signal, keep the walk compact, and treat dinner as a live-check constraint rather than a fixed recommendation. This guide is for sequencing the first night, not for ranking restaurants, promising church access, or solving parking in real time.
If you only do one thing
If you only do one thing, use Piazza Roma as the starting point and San Martino with Piazza Plebiscito as the center of gravity, then keep dinner within a short old-town walk. Check current access, events, weather, parking, restaurant availability, and opening hours before relying on the plan.