Normally 3 packs are enough for a full head, at most 4 packs.
You can always use the leftover hair later, if you are using hair 18″, you might need another pack. If you are getting fusion or micro then you will need to consult your stylist.
Treat this hair as if it was your own hair.
1) Using good quality shampoo and hair conditioner to protect the hair, it’s important to keep the hair soft and shiny.
2) You could use gel or spray styling products to keep the hair style.
3) Olive oil will be a good choice to keep the hair health.

Your hair extensions tangled due to dryness, oil & dirt build-up, salt water, chlorine and not combing(wide tooth comb) out your hair daily. Make sure to wash&condition your hair at least once a week, twice a week is better, use hydrating drops or consult your stylist for more help.

This hair can last for very long time depending on how you maintain it, treat it like your own hair and treat it like your own hair and take very good care of it in order to use longer. If you buy 100%  virgin hair and take good care of the hair is can last for over one year.

Different monitor has different display, the same color number may have a little color difference.

Human hair has natural protein, it is easy to tell by burning and smell, human hair will be ash which will go away after pinching, human hair will smell foul, when burning, the human hair will show white smoke while synthetic hair will be sticky ball after burning and will show black smoke. Moreover, human hair may have little gray hair and split ends, it is normal but not quality problem.