Your enamel wears away, or becomes eroded, two different ways, mechanically or chemically. Mechanically is through a toothbrush. Unfortunately, some people have the belief that your toothbrush needs to be a medium or a hard toothbrush. That is a disaster waiting to happen. That's how people wear through their tooth enamel, and I've seen many people where the lines go straight through their enamel-- terrible. Never use a medium or hard bristle brush, and never use those natural brushes you find in health food stores. They're terrible. Always a soft nylon toothbrush, that's the best. Whether it's a powered toothbrush or a manual toothbrush, it's the bristles that do the work.
Now, the chemical eroSion has to do with acids. That could be in food. Many foods that we eat are acidic in nature. And that includes your citrus foods and citrus juices, as well as in many mouth washes, which have very high acid levels. So if you're going to use many of those popular mouthwashes, which I would ask you not to do, don't keep them in your mouth very long because the longer you keep an acid in your mouth, the more chance you have of wearing away your tooth enamel.
See the recommended TheraBreath toothbrushes & more from this video, here.