How do you get an unsigned oil painting valued?

To get an unsigned oil painting valued, start by researching similar artworks to gauge market trends and pricing. Consult with a reputable art appraiser or auction house that specializes in your painting's genre or era for a professional evaluation. Additionally, consider obtaining a written appraisal for insurance or resale purposes. It's also helpful to gather any provenance or history related to the painting, as this can influence its value.