Craigslist can be a very effective resource. It is a massive marketing machine. However, within the recent past, they have decided to charge $25 to post in the Sales category. The good news is that getting flagged and ghosted is less than it used to be... and if you don't know what you are doing, getting flagged and ghosted can be pretty frustrating.
It can become pretty complicated pretty fast if you want to maximize its potential... using different email addresses and multiple IP addresses. However, if you want to keep it simple... kind of like Forrest Gump, "Stupid is as stupid does"... there is utility in learning how to capitalize on CL. Simply Google "Marketing on Craigslist" and you will find a ton of resources made by people who are currently doing it.
HERES ONE video that explains the process.
If you want to learn more about this topic and what other sites can be used, see THIS ARTICLE.