Yes, you should most definitely join Facebook groups. Ensure that you do some prior research before you join a group.
If it’s an open group, see what the group is about. Check how active the group is and when was the last recent activity. Whether the members discuss about fashion wear, home utilities or other products that you have to offer.
If it’s a closed group, then figure out from its name what the group could be about. See the number of members in the group and how active it is.