Is it better to have/use more credit cards to build credit history/score?
Increasing the number of cards is a double-edged sword credit-wise. There's a trade-off between the amount of credit used (utilization), number of inquiries and open accounts (fewer is generally better) and average length of credit (churning accounts means a shorter average). The main factor in your credit score is a good payment history. From what I've seen the number of made payments is not significant, but the number of missed payments certainly is. So making 10 payments on time is the same as making 1 payment on time, and making 1/10 late payments is just as bad as making 1/1 late payments. So the danger of getting many cards is that you lose track of when payments are due (or worse, you overspend and accrue more debt than you can afford), you miss even one, and you've completely negated any positive effect (if any). In other words, you won't build your credit score much faster by having 10 cards instead of 1, but you can certainly wreck it if you make a mistake. My advice is to not try and "game the system". Make your payments on time, use credit cards as sparingly as you can (don't spend money just to "get miles"), and your credit score will take care of itself.