Mountains are always a good idea, Parvati Valley, Kullu Valley and Kinnaur are a few places with good road connectivity, very low crime rate and a lot of tourists. Rajasthan, Pondicherry and Kerala are good options too. Go through the below attached article for more articles!
There are many beautiful places to remark how incredible India is.
You can visit Himachal Pradesh to make your solo trip amazing and unforgettable.Dalhousie,Khajiar,Chamba,Kullu,Manali,Rohtang Pass would be perfect for your solo trip.