If you are struggling with bad breath, brush twice a day, and floss once a day. Use a breath spray. Also make sure to "brush" your tongue, roof and sides of the mouth, gently. Make sure you eat breakfast; stay away from garlic and onions. Diet may affect one's breath; milk and dairy products make for strong teeth, but may not be the best for good breath.
Sugar-free or regular mints might work well, or gum. Some mouthwash companies have a dissolvable tape that you can put on your tongue. Problems with clogged sinuses may cause difficulty, especially with colds.
Dentures (false teeth) may cause problems. I would speak to a dentist, your family doctor, and even someone who deals with natural foods, vitamins and health remedies. Check with a doctor before trying anything, even "safe" products over the counter, such as remedies/pills.
And try not to breathe through your mouth a lot. And be aware of how close you stand to others. And make sure to visit your dentist every six months to make sure other things are happening in your mouth to case a breath problem, like a cavity.