The headline in the ad should be large, clear, reflecting not only the subject but also the purpose of sale. For example: "Sell house", "Sold the phone".
Making the announcement about the sale, it is necessary to specify technical specifications: model, date of manufacture, dimensions and so on.
It is desirable to provide a more detailed description of the products, paying particular attention to its advantages and avoiding disadvantages, unless it's a glaring defects. Disadvantages – subjective. It may be that you did not like in this thing for the new owner will not have value.
The defects should write and even take pictures. Just to not waste your time and the buyer if it turns out that he doesn't want to buy a product with a defect, no matter how insignificant it may be.
If the reason for the sale looks fine, it is useful to specify it. For example, "presented, and I don't need". The reason "sell the house because got neighbours-brawlers" better not to specify, otherwise you can scare your ads to potential buyers.
In the announcement about the sale , it is desirable to add a photo to sell things. Better if it is multiple photos taken from different angles so the buyer could get a full view. As practice shows, the announcement of the sale without photos is going to much less interested.
Don't forget to include price! If you do not believe in it and are willing to bargain, it is better to write about the price and specify that "negotiable". Not everyone wants to call and find out what price you had in mind.
Include contact data that is easy to find. Better with a mobile phone which has the property periodically to discharge and be out of range, to specify a home phone number or your e-mail address.