Every vehicle should be equipped with a basic emergency kit. That kit can help you out if you are broken down on the side of the road and have to wait for a tow truck to come and find you, or if some other kind of emergency happens while you are driving.
Emergency Kit Basics
Some things should always be in your emergency kit. Those things include road flares and reflective orange triangles. These two things have an important safety feature. They are used to alert other drivers that your broken down car is in the area, especially at night when it can be hard for other cars to see you. If you place the triangles and flares at regular intervals leading up to your car, they will catch the attention of other drivers, and give them a chance to get as far away from your car as the road allows. The flares and triangles can also give a tow truck driver or legal authorities something to find you by.
You should also have some kind of signal flag. The flag doesn't really have to be anything elaborate. A pennant that you can affix to your antenna will work, as long as it is a bright color so that it highly visible. Both white and blaze orange are good choices since they are both easily seen. If it is reflective as well the flag can be usable at night as well.
In addition to the basics, there are some things that you should have that change from season to season.
In the summer, you want to make sure that you have plenty of water in the car. It doesn't take much to get dehydrated in the summer, and you don't know how long you may be stranded. You should also carry snacks. Avoid salty snacks, since they will just make you thirsty. You may also want to carry a battery operated fan to help keep you cool while you are waiting for help. You may not be able to run your car, so you can't depend on the air conditioner. If you travel with small children, you should also make sure that you have diapers, powdered formula, if necessary, and something for the kids to play with.
In addition to water and snacks, you should also make sure that you have plenty of blankets to help keep everyone warm. If you are worried about space, the reflective emergency blankets that come in small packs are a good idea. You can also get some chemical hand and foot warmers that are compact and can be used to keep you warm. Make sure that you have extra winter gear in the car, such as hats, mittens, socks, and clothes like sweats. If you can layer on extra clothes, you can stay warmer.
Making sure that you are safe when your car has broken down should be your first priority. Once you are sure that you are safe, you should call a towing service to get assistance to help you get your car going again.