Your bike sounds similar to mine. Keep a brake on there. Seriously consider adding punture-resistant tires (I use 28 continental contacts) and front/rear lights (Enough to be seen, not deer shiners). These additions, plus whatever you need to fix a flat, and you will save yourself a lot of headaches on the road. Also, think about what you need when you get to work: change of clothes, towel, deodorant, wet wipes, etc. I'm a minimalist so I'm not a huge fan of commuter-specific bikes, fancy bike specific clothing, messenger bag/panniers, fenders, reflective gear. Give me a bike, my old backpack and helmet and I'm set.

I do almost 6 miles each way. I love it, uphill in the mornings means I have an awesome return trip a 5 each day. I keep a spare tube, levers, 15mm, allen set, Co2 pump, rain jacket, and usually some sort of granola, candy bar, or peanuts in my bag at all times. Depending on the weather I'll bring a change of clothes in case I get all sweaty and gross. I always have a fender on my bike. I wear a front and rear blinky and when I have it I attach a blinky to my hat because I feel safer if I can look right at someone and know that they have seen my lights.

When I first started making the commute it was sometimes dreaded, but the more I do it the more I look foward to doing it. Besides, science has proven that bicycle commuting is at least 9 times more fun than being in a car.

Get a rear rack, and some small panniers. For the commuter, they are better than a messenger bag, they don't leave you with a sweaty back.

Full fenders are great, too. I have SKS raceblade partial fenders on my Pista, and they work acceptably.

I live on campus at my school, so it's never a far ride going to class/work, but I always keep my multi-tool with me, and if I had some sort of smaller pump(come to think of it I need to buy a pump in general) I'd bring that, tire levers, and an extra tube or a patch kit.

A presta to schraeder adapter is also good to have in the tool pouch.

My commute is a measly 3.5 miles each way but it starts right off with a big-arse hill that gets me all sweaty. In this cold weather, I can take the hill slow and be okay but when it warms up I'll be a stinky mess by the time I get to work so I've decided to do the ultimate Fred move and WALK the dang hill.

When spring and summer get here, I'll still have to do the paper towel bath when I get to work; ain't no deodorant powerful enough to overcome Alabama heat and humidity.

I have the under-saddle bag that holds tools, tube, patch kit; a rack and some plastic fenders that I usually have off. Blinkies on the front bars and a Planet Bike blinkie for the rear.

I find that yelling at the crackheads usually gets them out of the way in the mornings. In the afternoon I brandish the frame pump. They show respect.