1. Always drink soda, juice or colored/acidic drinks through a straw.   It will protect the enamel on your front teeth from wearing down and looking thin or transparent.

2. Never brush your teeth right before or right after drinking soda, juice, or anything sweet.  It will only further rub the sugar and citric acid into your enamel.  Instead, rinse well with water and wait at least an hour before brushing. 
3. Floss, baby, floss.   Let's face it, flossing sucks, but so does having dirty, yellow teeth!  Choose your battles, people.   
4. Use a whitening toothpaste... it has the same ingredients as whitening strips.  I like Colgate Optic White.  And over time, if used every day, this makes a huge difference.   
5. Listerine Total Care Plus Whitening.  It's more expensive for a reason-- it works!
6. Gel whitening trays with 24% hydrogen peroxide for 1 hour a day.... it works better than doing the 8% of hydrogen peroxide over night.  Do this process once every 6 months.  This is the most fast/effective method I've used thus far.
7.  If you're seriously in a bind, take baking soda on a toothbrush and scrub for 1 minute every day for 10 days straight.  This works really well, too, even if you might vomit in the process. 
8.  If you eat hard candy, follow up with sugar free gum, raw carrots or celery.   This will help to get candy reminants out of the crevices of your teeth.  If all else fails, swish with water for a longgggg time.  Water melts sugar, remember?
9.  Don't think that diet soda is okay because it has no sugar.  Citric is just as bad, baby. 
10. Swish with flouride rinse after drinking soda.  I actually carry flouride rinse with me and use it a few times a day really quickly to prevent citric acid from damaging my enamel.  Obsessed much?  Nope.  Just a dentist's daughter.