How can I prevent tooth decay if I drink soda and chai latte?

Rinse afterward. Its not so much the amount of sugar, as it is the prolonged exposure. After sugary drinks, rinse with water or brush, of possible, to avoid the sugar sitting on the teeth. Also, dont sip all day long. Have the drink, finish it, rinse. The prolonged exposure, or constant bathing the teeth of sugar, keeps the ph in the mouth out of balance, and allows the "sugar bugs" to do their damage.
Fluoride. Some form of a flouride rinse or brushing for 3 min at a time helps to slow tooth decay.
Protect your teeth. Make an effort to protect your teeth. Brush twice a day with a Fluoride toothpaste. Clean between your teeth daily with floss or other interdental cleaner. Eat nutritious meals and limit snacking. Check with your dentist about the use of supplemental Fluoride and about use of dental sealants. Visit your dentist regularly for professional cleanings and oral examination.