1. Limit the consumption of refined foods (especially refined carbs & sugar) and anything artificial.
2. Consume more natural probiotics (good bacteria) and prebiotics (feed the good bacteria).
Probiotic sources include sauerkraut, kimchi, kombucha, and kefir. Prebiotics sources include green(er) bananas, onions, leeks, asparagus, and chicory root. If you’re looking to reduce your coffee consumption try the chicory alternative to feed your gut whilst you're at it.
3. Consume a variety of plant-based foods. A good way to do that is to use them as toppings (on yogurt, oats, etc.). Throw on some nuts, seeds, berries...
4. Supplement properly. This comes down to each individual and their needs, but a few good starting points are magnesium, zinc, l-glutamine, and digestive enzymes.