I'm planning on biking to work from now on. Any advice for this newcomer?

Hello bike commuters,

Recently, I took a job that will bring home a little less money then I have been making. Not a huge deal, but that got me thinking of ways I can save a bit of money every month. Aside from spending too much money on fast food, I also found that I spend damn near $250 per month in gas just going back and forth to work. Aside from saving money, I love the idea of getting excerise built into my daily routine. I live approximately 9 miles (14.5km) from work, and most of the roads on the path have a bike lane, or at least a sidewalk. I still need to pick up a bike for this, and I'd love any advice anyone might have.

Thank you all.