Watch your mouth

The five main steps in maintaining good oral hygiene are:

Flossing (at least once a day)
Done properly this will remove the plaque and particles of food between your teeth, and under the gumline. If you're not sure how to floss properly, a quick Google will provide hundreds of sites eager to show you how.

Tooth Brushing (at least once a day)
Electric toothbrushes have come down a lot in price over the past couple of years, and while there's no proof that they're more efficient than 'manual' versions, the fact they require less effort does encourage you to spend more time on making sure your teeth are properly scrubbed. Again, Google will reveal plenty of info on brushing techniques.

Tongue Scraping (at least once a day)
Tongue-borne bacteria is the major cause of bad-breath. It can be scraped off using your toothbrush, or a purpose-made tongue scraping device. Be prepared to fight the gag-reflex, and make sure you go back as far as you can, as this is where the really 'orrible bugs reside.

Nutrition
OK, you know about avoiding sugary stuff, especially sugary stuff that will stay in your mouth a long time (boiled sweets, mints, Werthers Originals). Drink water after eating sweets to dilute/rinse the nasties. Hard toffee is excellent for removing fillings/ceramic crowns from their mountings.

Regular check-ups
Visit a dentist at least once a year whether you think you need to or not. They can spot stuff going wrong before it becomes painful/even more expensive.
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