I have participated in paid post sites in the past which pay me, as the blogger, to write about a site or service.But there are many free guest posting sites from where you can get good quality dofollow backlink.Here is some sample sites
1.behance.net
2.livejournal.com
3.houzz.com
4.deviantart.com
5.medium.com
6.dailykos.com
7.hubpages.com
Thank you for sharing!