About tonsil stones: dental hygiene is incredibly important.
There are also some medical factors. Some people are just made with tonsils that are more cryptic than others and are more prone to getting them. More attention to hygiene.
Drink plenty plain water. The main risk factor is dry mouth, especially overnight. If you take medication that can or does give you a dry mouth, yet more attention to dental hygiene. Also keep water beside the bed and swig it when you stir in the night.
Stick mostly to water. Fizzy drinks, hot drinks, and thick drink-y type things don't flush out the mouth, they hang around. Also the sugar in fizzy stuff and juice provides glucose for the bacteria that make tonsil stones to feed on.
Make sure your mouthwash is a non-alcohol one. Alcohol mouthwashes dry out the mouth and will make the problem worse.
If you don't use mouthwash and gargle it after you brush morning and night, start doing that. You need to gargle because you need the entrances to the tonsil crypts to get jostled around to work the crap out. Try singing some high Ahhh's whilst you brush too to get the tonsil area jiggling.
Some people with a real problem swear by Waterpik flossers to try and push the stones out. Try at all costs to avoid touching the tonsils directly - they bleed incredibly easily and damaging them makes infection likely.