I started bike commuting 25 mins 9 years ago on a 30 yr old road bike that only one brake, a rear derailed that did not move at all, and some kind of kinky, pealing and chipping hard plastic molded to the handlebars instead of bar tape...and tires that looked cracked all my over...I wore a backpack.....

...I've since upgraded to a $ 200 wal-mart hybrid, with lights and a rack to which I strap down a bag with clothes with bungee cords. I now go 15.miles round trip.

I say start simple, then you'll figure out what you need as it goes...but be ready to fix a flat!