Success with craigslist really depends on several factors.
1. Be The One to Blaze the Trail. Is your area's craigslist well known and widely used? I'm in the Bay area where craigslist was born, so it is a given that this will be where it will be most active. If your area isn't often used --- yet ---be the one to use it most often.
2. Repetition, repetition, repetition. How often do you post your listings? 2-3 times a week is a good number, as long as you have 48 hours between postings
3. Catchy headline --- be creative. Use humor. For example, if you're posting a fixer --- you can headline it by saying "What a dump!" or "You can own this dump!"
4. Use VFlyer.com and Postlets.com to create your flyers with multiple pictures. After taking the time to create the flyer once, when posting on craigslist later, it's simply copy/pasting the html.
5. Pictures, pictures, pictures! Post the maximum allowed. When using Postlets, you can post up to 6 pictures, free. With Vflyer I think it's 24. Just like posting on MLS --- your primary photo should be a knock-out. And you should provide as many pictures as possible.
6. Create a craigslist account --- makes posting a breeze. You can log on to your account, edit/change/delete. You can also copy paste using old postings if you're not inclined to log on to Postlets/Vflyer again
7. Specify the City when posting real estate for sale. If you don't, it will drown in a sea of other postings and they'll never find you.
8. Put in KEY words or the buzz words of the moment. For example, "Not an REO!" or "Not a Short Sale!" --- people using keywords to find such listings will find yours, too.
9. Email your database. If you have listings, email the posting to your clients and prospects. This will underscore your being "wired" in other ways, and may even set you apart from others who are not using this medium.
10. Post your open houses. Email an invitation via craigslist to prospects to come see you during your open house. Another way to advertise your listing for free.
Like anything else, it may take time to germinate. But for me, posting on craigslist is part of my marketing plan. My clients and prospects use craigslist --- so wherever they are, there I am!