Its really frustrating when get into your car and it doesn't start especially when you are on a hurry, the reason for that could be silly like your battery charge is low so here are some few tips to maintain your car battery in good condition :
Check the fluid level and add water when needed, don't use tap water, use only mineral free water, distilled water is the best
Check the acid level in battery every 6 months
Clean the poles when need from any rinse or corrosion using hot water or baking soda and water solution
To prevent formation of rinse on poles you can use petroleum jelly (Vaseline)
Turn on the car at least once every 3 days
Turn off the radio, lights.... before leaving the car
Avoid operating radio or so for long time when car is turned off
Replace your battery once every 3 years ,after 3 years the batter efficiency decreases and its time to replace it