There isn't much you can do to prevent them, but you CAN remove them. I noticed someone mentioned at home whitening. Yes, they work, but they are expensive and temporary. Instead, get a bottle of hydrogen peroxide from the pharmacy (about $1 for a large bottle) and a box of baking soda from the grocery store (also about $1). Use a little of each on your toothbrush each night. Baking soda does NOT taste good, so I also dip my brush in peroxide, then baking soda (not too much) then toothpaste over top to mask the taste. It tastes a little like soap but you'll get used to it fast and it leaves your mouth feeling SUPER clean. It'll remove all the surface stains that coffee leaves, but it's not so harsh that it'll make your teeth jumpy and sensitive and damage the enamel. It's a very gentle cleaner, and it does work well. If you can handle the taste, you can also make a peroxide and baking soda paste and use it just like toothpaste, but I personally still need the toothpaste to mask the soapy taste.
Plus just 2 dollars will last you MONTHS where are whitening strips will last you only a few weeks for 40 dollars or so, and they'll leave your mouth very sensitive.

Good luck!

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