Eating Habits and Tips
A lot of the odour from the mouth will be coming from the items we consume. As such it is good to avoid too much of any 1 thing, and in particular for bad-breath, that would be foods such as onion and garlic, or anything similar which can sour your breath. These foods can also induce acid-reflux in those that suffer from it.
One natural remedy to try would be to chew a handful of cloves, fennel seeds, or aniseeds. Their antiseptic qualities help fight halitosis-causing bacteria. Similarly if you prefer something fruity, chew a piece of lemon or orange rind for a mouth-freshening burst of flavor. The action of chewing will naturally displace food particles. (Wash the rind thoroughly first.) The citric acid will stimulate the salivary glands. Both things combined will help wash away Odour-causing bacteria from the oral cavity.
A word of warning - be careful of the acidity in citric fruit - be sure to rinse with water or drink water following citric fruit. For something less acidic but still just as fresh, you could try chewing a fresh sprig of parsley, basil, mint, or cilantro. The chlorophyll in these green plants neutralizes odours effectively as well as being a healthy source of key vitamins and minerals.