Best technique for hills?

I live in the Washington DC metro area and drives around my area is generally stop and go, somewhat hilly (small hills though), between 30 and 45 mph.

Of course, my short daily commutes to and from the Metro station yield me pretty low gas mileage (around 34), but I also have slightly longer drives when I go shopping or running errands.

What are your opinions about the best way to handle the little up and down grades? Should I accelerate slowly up the hill, or push it? Or should I push the gas as I'm coming to the bottom of the hill and hope that momentum will help me up the next?

What about at highway speeds? What's the best way to handle hills?