I don't really advertise. My wife sells at work so word of mouth goes a long way. She will sell about 3 to 6 doz at work a week and there was a big bump around the holidays. I also sell to a woman who does Farmers markets, every week during the summer and fall, monthly Nov to April. She will buy anywhere from 6 to 15 doz if I have that many in. So work is an avenue, a sign if front of your house ,craigslist, local paper,fliers and roadside stand(or back of your truck) on a busy road. Check local and state laws before doing anything though.
I started out out giving my eggs away to relatives, friends & neighbors, but they would take free ones, but wouldn't buy them.
So I put an ad on Craigslist. Was answered by a baker who wants to buy all I can sell him every week. Then was answered by another chicken-owner who sells his at a local farmers market. So I wholesale all my extras to them.
I sell all of mine by word of mouth to co-workers. I made a facebook group (I know, my generation...) and the people who are interested in buying the eggs joined the group. When I have extras, I just post something on the group and I usually get a reply within an hour or two from someone who wants them!