What positive steps can be taken?

What should we do to counter terrorism? Bruce Schneier offers this advice today:

Counterterrorism is most effective when it doesn't make arbitrary assumptions about the terrorists' plans. Stop searching bags on the subways, and spend the money on 1) intelligence and investigation -- stopping the terrorists regardless of what their plans are, and 2) emergency response -- lessening the impact of a terrorist attack, regardless of what the plans are. Countermeasures that defend against particular targets, or assume particular tactics, or cause the terrorists to make insignificant modifications in their plans, or that surveil the entire population looking for the few terrorists, are largely not worth it.