Long Bridges and Crossings
On a large puzzle, a bridge blocks every bridge that would cross it. Once a long bridge is certain, look along its length for islands that just lost a neighbor: their remaining choices shrink, and often a forced bridge appears on the other side.
Keeping the Network Whole
With thirty islands, it becomes easy to close a group by accident. Before the last bridges, check that every group of linked islands still has a way out; at Medium and Hard, that check is often what decides the final bridges.
A Step Up From 9x9
The 11x11 puzzles suit solvers who know the 9x9 size well. The reasoning stays the same; the puzzle simply asks you to hold more of it in view.