Battery
Finally check your battery. If they're anything like the image below they should be cleaned immediately. Dirty terminals like this could cause your car not to start. The cables should be clean and tight and free from corrosion build up.

BATTERIES CAN BE DANGEROUS IF HANDLED IMPROPERLY THEY CONTAIN ACID AND SHOULD BE HANDLED WITH CARE. WEAR PROTECTION EYEWEAR AND GLOVES WHEN WORKING ON BATTERIES. IF YOU HAVE QUESTIONS OR ARE NOT SURE SEE A QUALIFIED TECHNITION BEFORE PROCEEDING.

To clean corroded terminals use a mixture of baking soda and water at a paste like consistency. Apply it to the terminals and let it sit for a few minutes then rinse with plenty of fresh water. The battery should look like the image to the left with the terminals free of rust and corrosion.. They should be tight.

BE VERY CAREFULL NOT TO GET ACID ON PAINTED SURFACES OR YOURSELF. RINSE ANYTHING THAT COMES INTO CONTACT WITH THE ACID OR CORROSION WITH PLENTY OF FRESH WATER.