people love to tell me that no-one uses craigslist anymore...
Yet somehow I sell sheep, chickens, ducks, cars etc on craigslist.
facebook is just too toxic.
Craigslist takes some time (and a well drafted ad) and you need a way to weed out time-wasters without scaring away real buyers - I get a phone number and make a brief friendly call right away.
Each year it gets a little easier as more people in my area know I'm the person to contact about sheep. Folks refer buyers to me, and when I run out of lambs I refer buyers to other sheep people I know. I always have the animals for sale ready in a separate pen easy to load when the buyer arrives.
I keep a list (google sheets) of people who are interested in buying animals for meat. This comes from casual conversation when I'm out and about "O, you raise sheep? What do you do with them? wool?" "Wool, live keeper lambs, I sell whole animals for meat." "I'd love some lamb meat." "I can put you on my call list, I usually have them in the Fall for $400-$450 each"
my final tip - something I've seen friends really struggle with is TIMING. Setup your flock decisions when you make your breeding plans. If you are clear on your own plan then you will know who's for sale before its time to sell them. My friend wavers and wont commit to how many goats to keep because she's attached to them all, by the time she's realized she's not going to keep them all its late summer and **the serious buyers have already found their new goats for the year**. In comparison I know how many I want to breed, how many I want to grow as replacement breeders and how many rams I want, so when lambing concludes I can pretty quickly decide who to keep and who to sell, I list them before they're even weaned and settle my keeper sales late spring early summer.
In my unsubstantiated opinion Facebook is too convenient for too many people, as a net its brings in too much by-catch, craigslist is the slow and steady method to bring in the buyer you actually want.