How to make a good SEO for a classified ad site? 

To make a good SEO for classifieds sites and classified ads UAE, I would suggest adding quality content in Hompage, using main keywords.

The URL uses the primary keyword in the title and synonyms and LSI keywords in a single classified ad description. Link-related products using related keywords with internal links.

Metadata is essential too. Use an exact keyword in title and description, and only when possible, in URL too. Don't do keyword stuffing. Try to be natural and try to add a CTA in every meta description.

Then you can analyze how it is working for you in rankings and visits if it works well to do more social links with bookmarks.

Now you have to decide to make more links or improve your site structure and content. You can guess it is paying attention to bounce rate, CTR, pages per session, and more.