Is that the typical way to do it or did I characteristically do it the ugliest possible way?
I prefer to ensure that the string is always NULL terminated:
myString[j] = Serial.read();
myString[j] = '\0';
Your way will work since you are using a while loop and terminating the array at the end of the while loop. My way, though, means that I don't have to remember to terminate it at the end of the loop.
Also, if you do any error checking, to be sure that there is room in the array for the new character, you also need to ensure that there is room for the NULL. With my way, you'd check that there is room for the character and NULL, once, and add them both.