Helen Hill, president and CEO of Explore Charleston, has some words of advice for anyone visiting the Holy City this year.As someone who grew up visiting Charleston, South Carolina, every summer—my family vacationed on nearby Kiawah Island—and then eventually moved to the Holy City for a few years in my late 20s, I have a special place in my heart for this buzzy corner of the Lowcountry. Sure, it’s the opposite of undiscovered, with repeat appea…