How do I clear a screen efficiently

Whenever I try to make a game or something that requires the rapid clearing of a screen, I've used system("CLS"). I now know that that is not good to use so I tried using a for loop to print new lines rapidly. While this works it looks really weird and less clear. I've seen people try to use STRING to clear a screen but whenever I try it it never works. How can I clear my screen efficiently and cleanly.