It depends on what kind of bike you have and where you live.
The fancier the bike, and the less populated the area, the more I'd recommend eBay instead of craigslist or some other local listing.
Bikeflights does a great job with shipping in the U.S.
Be sure to list the size in the title, and list as many details as you have. No need for narrative descriptions about how it does sweet jumps.