Halkidiki is generally a safe destination for solo female travelers. Local people are friendly and hospitality is a big part of Greek culture. Petty crime may occur, as in every tourist area, but violent crime is extremely rare. However, always exercise common sense, be aware of your surroundings especially at night, and take the same precautions you would take in any other location worldwide. With these measures, you should have a enjoyable and trouble-free visit.