Inspect these items with an SEO Audit:
1. Start with the domain, is it indexed on Google and Bing?
2. Test the inbound and outbound links.
3. Test desktop and mobile loading speeds.
4. Look for optimized images with Alt tags.
5. Inspect headers, url file names, titles, meta descriptions, meta tags
6. Check structured data. Schema / JSON. Do you have JSON?
7. Check content, do you have enough text on each page?
Once you've determined the areas that need work, you can refine the SEO on your website.