L.R.
While it's good to have one bank card and use it once in a while to keep a good credit rating, if you have a lot of them it may decrease the amount you can borrow. There is a credit limit on the cards, and they may add the limits and assume you have that as debt. I was told that 15 years ago by a bank, so even though I always paid off my cards each month I canceled all my store credit cards.
There is another way to get credit. You can get a small personal loan from a bank and pay the monthly bills. You can't skip a month for any reason (even if you put down extra money one month). Years ago, I got a loan from my credit union for a computer ($1000) for one year. Building credit this way is good if you don't want to be tempted with a credit card.