On any island map, you must get a good economy to start off with. This means building scvs non-stop, and getting gas as soon as possible. Terran's basic unit is an anti-air unit, so building 2 barracks at each island will ensure that you hold them as long as you build marines non-stop as well. Now once your factory is done, you can either turret your base to protect against wraiths, or build a starport. You should be able to expand to the 2nd island, by floating a command center there. From here you can decide your course of action.
