Now the fun part! About two or three feet before your hands reach impact, assertively rotate them toward the target. Imagine you're gripping a screwdriver and turning it counterclockwise. This closes the clubface, generating big-time power.
It's important to note that you can turn your hands too early (you'll hit a hook) or too late (a push), but you can't turn them too much. So really go after it with an athletic motion. Also, your lower body should stay quiet: excessive hip clearing and swiveling is wasted motion. The legs should support your upper body, not drive the swing.
Take a look at this swing sequence from a first-person angle (go right to left...sorry southpaws). The open clubface (far right) closes through impact; the toe should almost point to the target (far left) a couple of feet after impact.