Patch kit and take the time to practice removing the wheels and tires at home- do it until you can do it with your eyes closed (might have to do so at night and in the rain sometime- and you don't want to take the time to figure out to change a flat at that time). Carry a spare tube and patches. Bunch of us swap out the tube and then patch the bad one after the ride.

Lights. Get at least two rear lights. PBSF Turbo, PDW Radbot 1k, Cygolite Hotshot are some decent rear lights that aren't too pricey. Bunch of people like the Hotshot because it's USB rechargeable and you can program intensity and flash patterns.
Front lights- you'll want as much as you can afford. It's better to have too much light and scale back than not having enough and wanting/needing more.