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nothing difficult, ensure your website has high-quality, relevant, and updated content to attract organic traffic and earn backlinks from authoritative sites. Build a strong backlink profile by earning links from diverse, reputable sources while removing toxic backlinks. Optimize on-page SEO elements, including meta tags, internal linking, and mobile responsiveness, while improving site performance with faster loading times. Ensure your site is indexed correctly by submitting an updated sitemap to search engines and addressing technical SEO issues like broken links or crawl errors. Consistent effort and monitoring tools like Moz or Ahrefs can help you track progress effectively.
I did same for one of my friend website who is providing services as airbnb interior designer.

To reduce your spam score, optimize your email content by avoiding spammy words, excessive caps, or poor grammar, and maintain a good balance of text and images. Use a verified domain with proper authentication (SPF, DKIM, DMARC), and ensure your subject lines are clear and relevant. Provide an easy unsubscribe option, manage your email list by cleaning invalid addresses and avoiding purchased lists, and send emails at a consistent, reasonable frequency. Test emails with tools like Mail Tester to identify issues, and warm up your IP if new. Finally, avoid embedding large attachments; use links instead.
The answer is simple you can go and make a backlinks file that you thinks are spammy. Submit that file in GSC and just get rid of them.
I had the same issue with one of my friends' website and I did the same. Now its good going.