I usually commute (28mi round trip) in 'baggy MTB shorts' and a cycling jersey. I know it is just vanity, but when I have to stop for errands on the way there/home, I like not walking through wal-mart/target/grocery store in spandex. I also wear wicking socks (I have bike-specific ones - as silly as it sounds to spend money on biking socks, they help a lot) as well as crankbro's eggbeaters (candys). I use a fairly relaxed shoe with them - I can walk around without feeling the cleat, which is nice if performance isn't your main goal.

Get good locks, and replace any quick releases you have on your wheels/seatpost! I see bikes locked up missing a wheel or seat all the time.