Ask HN: What features do you need for an ads website

Hello, I am planning to develop a free ads website, and I was wondering what features do you need or what features are existing classifieds websites missing?

I know there's a lot of competition on this niche but I am planning to launch few websites in different Europe countries (UK, Spain, Italy, etc).

I have the website format already and I want it to be easy to use and with useful content. Ads will be added with no registration required, and all ads will be manually approved, so no medicine, work at home, crappy ads will be listed.

Thanks.