I am not experienced but what i learned these days, i can share it with. You can sell your domain few ways.
1. Selling it in a marketplace like Sedo , Flippa and Afternic . If you have good domain and you are sure you it will be sold through sedo.com , then go for it. Otherwise you will lose money. If your domain is .io, tech related or domain hack, then go for flippa.
2. Through you own website ( if you have one )
3. The best way is through email marketing. Search for leads. send them email ( to the point ) and you will get a good customer. But don't overprice it. If u think your domain deserves $ XXX, then ask only $ XXX , if u think your domain deserves above that then ask them that.