Seems you've gotten just about everything as per good advice. The other thing I would suggest, if this is a cold area:
For your trunk:
Put a THICK WARM blanket in the trunk in case you get stranded.
Get a couple of flares... So you can be seen in case it is night time or a blinding snow
Double check your spare tire once a month during the winter. They have a tendancy to go partially flat in the winter months.
1 big bag of kitty litter. For traction in case you get stuck.
Get a cell phone from the local police department. They're usually free, and will only dial 911 in case of an emergency.
As it has been said already, drive slower. If you find yourself in a situation where you have to stop faster than you would like, putt the engine in neutral, or taking it out of gear (stick shift) and hitting the breaks will slow you faster than if you just pump the breaks. When the engine is in gear, you are fighting against it. You'll maintain a lot more control in your 'unexpected' stop when the engine isn't still trying to push the car forward.
One last thing... even if you're doing great, sometimes it's the idiot sliding into the ass of your car that can cause the problem. Definately keep an eye on cars approaching from behind when you're sitting idle at a stop light/sign. If you see they are going to hit you, same as above. Take the car out of gear, be ready to hit the breaks and turn the wheel into the curb. It'll help you keep from being pushed out into traffic. If you are hit hard enough, the butt of your car will usually go into traffic instead the front.
Take care out there!