Credit cards can be a great tool for building your credit. However you don't want too many cards that you:
A. Can't keep track of them
B. Take out so many that it utilizes our available credit limits based off your income. ( ex. You make 150k a year but you have 8 CC with 5 to 10K limits Cc companies and lenders will flag you for seeking too much credit once you start borrowing more than 30% of your income )
C. Have so many yearly CC anual fees that it adds up to a car payment. ( if you have 8 CC with an annual 100 fee. That's a lot.
I personally keep credit cards that provide additional value for me: An airline credit card, a hotel Credit Card, a clothing store CC and a cc from my financial institution.