Ruse is considered to be quite safe for solo female travelers. Violent crimes are relatively uncommon, and the locals are generally friendly and welcoming towards foreign tourists. However, like any other place, normal precautions should still be taken. It's advisable to keep an eye on your belongings and avoid deserted or poorly lit areas at night. The language might be a barrier if you don't speak Bulgarian, but English is spoken by the younger generations and in tourist areas.