Washing: Avoid overwashing. Use an oil and sodium chloride free shampoo. Make sure to wash and rinse in-between extensions. Pre-condition ends lightly before shampoo if the hair feels dry. Use a moisturizing deep conditioner weekly. I like the Kevin Murphy, Amika, and Davines lines. I love the Norwex shampoo as a cleansing and scalp balancing Shampoo.
Styling: It is crucial you do not go to bed with wet hair. Use a light leave-in conditioner and/or heat protecting cream. Let hair air dry as long as possible prior to blowdrying. I like Keracolor Purify Plus leave-in and Sexy Hair Heat Protecting Spray. Once dry, its important to brush and oil the hair at least once a day. Amika and Verb oil are great
Sectioning: When washing, brushing, or stying its important to section and separate hair. It's very easy (and it's something hairstylist do with all of their clients during hair cuts and styling), efficient and gentle. I will recommend a size for you to try.
Brushing: Finger comb first with detangler. You will need 2 brushes. One for detangeling brush when damp, and one boar bristle brush for dry brushing. It is recomended to dry brush at least 2x a day after applying an oil, but do your best. Wet Brush makes both types of brushes.
Sleeping: Brush hair before sleeping. Sleep on satin pillowcase or in a satin hat to keep hair health and tangle free. If you don't have those, you can lightly braid to avoid tangling.
Swimming: Swimming can damage the integrity of the hair extensions. But if swimming is a must, there are methods that stay in place (although hair may need to be replaced more often).
***Sunscreens cause discoloration in blonde extensions. Use only Mineral sunblock/sunscreen with titanium dioxide, zinc, or both
It's important to maintain regular appointments to remove your extensions from the growth point back to the scalp. This keeps it more comfortable and strong. Maintenance can vary with extension installations, length/texture/density differences, and lifestyle changes.