Our car batteries take a beating during their lifetime. And, that life time is determined by how they get treated while installed in your car. There are environmental and mechanical factors that are constantly working to shorten the life of your battery and there is not much you can do about it.
Some car manufacturers and some clever people are putting the battery in the trunk. What this does is take it out of the hot engine environment. The high temperatures in the engine compartment do not help the battery at all, so moving it to the trunk will extend its life somewhat.
If your car is parked for a significant amount of time without being driven your battery could loose its charge and not operate very good. Leaving a trickle charger on your battery will help prevent problems. Also keeping your terminals clean will help you start your car, corroded terminals will prevent good contact with your cables.
The accumulation of sulfate on the plates will reduce your batteries capacity to charge. This buildup of sulfate will corrode the lead plates to the point they will start to flake off. This is going to reduce that cells ability to take a full charge.
Batteries that have died or are about too, can be reconditioned back to almost new condition. There are processes that allow you to remove the sulfate from the plates in your battery and return it to a useful battery again. These procedures are not difficult to do and can be done right at your home.