I used john frieda get it straight shampoo and conditioner. Once every 3 days is about all you need to leave between shampoos.
Do not brush your extensions when they are wet. Next time if you choose to get your extensions redone go for the sew in type, they look better when they grow out and are easier to care for.
Don't use shampoos that have too much protein in them, it will make the hair swell. Do not bleach the extensions. If you know how to blow wave, your extensions will look really good.
Hope this helps a bit.