Yangshuo is a popular tourist destination and is generally considered safe for solo female travelers. The local people are helpful, and apart from some occasional minor scams, violent crime is rare. As with any travel destination, however, it's always necessary to take common-sense precautions like staying aware of your surroundings, not venturing alone late at night in remote areas, and not accepting rides or guides from strangers. Many locals know enough English to help if needed and there are plenty of expats and travelers around if you need assistance.