Bike as if my life depended on it lol.
My computer has a little arrow showing if im above or below my average speed. So I just try to keep my speed above the average as much as possible. The steep hills I go up around 15, the bridge I go over, I hit near 30 on the way down and hold it for a while and eventually stay at 20 till I get to a light a mile away.
One trick at lights though, look at the pedestrians. At stop signs and lights, I look for pedestrians jay walking in my same direction, if they stop and look, I'll keep my speed up and jam on the brakes at the last minute then stand and get back up to speed. If they cross, that means a car isn't likely to get into the intersection, so I just run the light at full speed.
I think this summer I'll save myself for taking out the road bike on weekends and stop treating my commute like a time trial.