How to Take Care of Hair Extensions

Let's start with the basics: shampooing. Be sure to use a gentle shampoo and conditioner, and don't skimp on quality. Don't ruin your hair and/or extensions by trying to save a few dollars on the cheap stuff. Some shampoos may actually accelerate the rate at which the bonder is broken down.
As far as coloring your hair and extensions, plan ahead. Color your natural hair the desired color before your extensions are applied. Your stylist will then color-match your extensions, whether synthetic or real, to your new color to make your purchased hair look like the real thing. Highlights can even be added by adding different colored extensions in the same way as highlights applied to hair pulled through a cap. If your roots need a touch-up before you need to change your extensions, it is best to leave the coloring to your stylist.
When it comes to styling your hair, it totally depends on the type of lengthener you have. If you have real hair extensions, most of your styling tools can still be used in the same way. However, with some types of synthetic hair extensions, more care needs to be taken. As with everything else, speak to your stylist. They will be able to tell you all of the styling rules specific to your type of extensions. Also, feel free to style your hair in ponytails, braids, buns, and barrettes as you would normally.
With summer coming, you won't want to miss out on dips in the pool or ocean because of your new hair. Be sure to always wear a swim cap made of latex. Carefully comb out any tangles that may be present, starting from the bottom and working your way up. Once the hair has been detangled, braid it into two braids to ensure that all of the hair is protected and tucked neatly under the cap.
After your swim, make sure to wash your hair immediately to remove any potentially damaging chemicals that may have gotten under your cap. Use your imagination and make your swim cap unique. Add some sparkle or bling to show off your personality.

With natural extensions, a special solvent is applied to the connection to help release the bond. Then, the decision is yours. If everything was done properly and your natural hair and scalp are still in good condition, you may choose to have new extensions added on the same day. If there is damage to either of them, it would be advisable to fix the problem before adding more hair.
I hate to sound like a broken record, or should I say a skipping CD, but talk to your stylist frequently to ensure a good experience with your journey into Rapunzelville. There are many things that could go wrong, so do your homework and find a stylist who is experienced and whom you trust.
I would also strongly suggest asking for references and speaking to clients who have had hair extensions applied. Ask to see pictures; a picture is worth a thousand words. If you look at an "after" picture and like the "before" look better, move on to another salon. Remember, you are paying the salon, so make them work for you!
See also: Hair Extensions Q&A