...introductory rates? Zero % introductory rates are temporary, I can transfer and purchase during this period and when interets rate starts I can open another credit card with 0% rate and close the one with interets rate, if I do this once a year , will it affect my credit score?

[Hedwig]

Closing the accounts will lower your score. Keep the card open, just transfer the balance off to the new card. Then use the old card occasionally for something that you can pay off at the end of the month.

This way, your ratios will stay low, and your length of history will grow.