You want to counterbalance the fact that you opened some new account by opening even more accounts and then close them.
If you are worried about your credit score, certainly don't open more credit card accounts. Having too many credit accounts open, means that it is possible that you spend too much on credit and not able to pay back. This is often a cause why a credit cards are refused which leads to bad credit scores.
I am not a expert but I think one should not have direct access to credit more than 3 times one's salary. The number may vary per person. The larger salary the more disposable income, etc.
To get good credit scores, it is far more important that you always pay the full amount off each month.