Make sure there is enough gas in your vehicle to get you to where you are going along with a little extra, you can't always plan on traffic, accidents, or detours.
Keep Your Doors Locked & Windows Rolled Up
Check the inside of your vehicle prior to getting in. Make sure nothing looks out of place.
If You're Being Followed, Don't Go Home
This is especially important if you know that there is no one else at your house. Let your pursuer know that you know that you're being followed. Change speed and direction. Then head for a place of safety; someplace that is well lit and has a lot of people present. If you know the location, head for your local police station.
Keep Your Cell Phone Handy
This lets you pursuer know that you are able to contact law enforcement and have access to help should you need it. It also provides some comfort if your vehicle breaks down, you can always call for assistance.
Avoid Parking in Isolated Areas
Always park where you can see the vehicle coming out and others can see you getting in. Special attention needs to be paid when parking in underground or secluded areas.
Don't Pick Up Hitch-hikers
While being considerate to the plight of others, you also make yourself an easier carjacking victim by inviting strangers into your vehicle.