The best way to fix car trouble depends on the problem itself. Fixing a battery that has been drained because the lights were left on can be as simple as a jump start with a set of jumper cables. However, fixing a slipping transmission can be an extremely complex and expensive job. The best place to start when fixing a problem is to properly diagnose the cause of the problem. Once you have determined the issue, you can then assess what will be needed to repair the problem. If you cannot do this on your own, then seek the help of a professional mechanic.