Brushing your teeth on a regular basis is the single most important thing you can do.
Most of the time bad breath occurs because of left over food particles and/or bacteria in the mouth. Thus, if you want to stop bad breath, the easiest way is to brush your teeth at least twice a day. It should not take a long time for you to start noticing and feeling the difference.
Another very effective way to curb bad breath is to rinse your mouth after brushing. You can rinse your mouth with mouthwash or even plain old water. Depending on the seriousness of the problem, both should be quite effective in reducing the frequency of bad breath.
Are you having issues with bad breath?