You should put the title of the posting in the main ad too – not just in the title field – and you must put it between h1 tags. This will give your ad a huge edge in the search engines.
Craigslist automatically puts the title in the TITLE field between h2 tags, but that is not enough if you want to get ahead in a competitive industry: you need to put your own h1 title in the main body IN ADDITION to the one in the title field.
With BackPage you should do the opposite: Put an h2 title in the main body, because BackPage puts the title in the TITLE field in h1 tags (surely a more logical approach than that of Craigslist.)
More generally, you should use classical SEO principles when producing your ad copy, and take full advantage of the HTML that Craigslist allows: bold, italics, underline, etc.
This will ensure that your ad’s appearance on Google’s first page will be by design rather than by accident.
