I just started commuting to work by bike a few weeks ago and it's pretty great! I totally agree with someone here that said that the route you drive may not always be the best route to ride. I ride the bus in the morning and bike for 2 miles so I don't show up all sweaty to work. Then I bike all the way home and while my driving route is the shortest in terms of mileage, I opted for a longer route that is 75% on a bike only trail. I don't like stressing over all the cars so the bike trail has made me feel more confident about going to work by bike. The other 25% is on a very busy street but it has a wide bike lane with enough room for parked cars and several bikes.

Stop at red lights, follow traffic rules and signals, and it's all good!

I just want to add a question. How do people handle left turns? Right now I dismount at the intersection and walk my bike across. What's the safest way to take a left turn lane? Do you take the entire lane?