Lot many places in south india like devotional and enjoyable trips. where you want start is the first step then you plan 4 beautiful states are included in south india all are different culture
If u love hill stations then you can choose coorg,wayanad,valparai,kodaikonal,sahyadri ranges hill stations if you love beaches,you can choose Varkala,dhanushkodi,pondichery if u r a nature lover go to Kerala road trip
Hampi servers the purpose well for a first time solo traveller. It's safe, easy to reach and heck of an experience. Try exploring Hampi along with Badami, pattadakal and aihole. But if you are looking for some peaceful nature time you can go to ooty.
Start with Pondy...it's serene and has its own charm..very safe and beautiful place..then there r many places like coorg, Chikmagalur, Hampi, Kodaikanal, Ooty, Mangalore, Gokarna, Murudeshwar...etc