1. It's Visual.
Visual content is treated more favorably in the Facebook world. Visual content is also more engaging in the ever-changing News Feed. Therefore, it is more likely to catch the eye of your potential customer. No matter what type of ad you create, your image needs to be visually appealing and attention grabbing.
2. It's Relevant.
Relevance is critical for success when using Facebook advertising. Don't forget that you are spending money when someone views or clicks on your ad. If you're showing ads that are not relevant to your target audience, then you are wasting your time and money and you will most likely not gain success with advertising.
3. It includes an enticing value proposition.
A value proposition tells the reader why they should click on your ad to learn more about your product or service. How is your product or service different from any other?
Your value proposition should be believable. Saying your business is the best in the world will not make people come to your business Page, but perhaps offering a 20% off coupon will. Or, maybe adding social proof will help; something like, "Voted best Real Estate Company for 10 years in a row by D Magazine! Get $500-$1,000 back at closing on your transaction with us!"
4. It has a clear call-to-action.
A beautiful and relevant ad is great, but without a call-to-action, your viewer might not know what to do next. Add a call-t0-action like "List your property with us and save _%," or "Offer ends soon" and add a sense of urgency to your viewer. Your call-to-action should encourage people to click on your ad now.
Read about what ads NOT to do and see some of the Best Examples here.