Most experts in the Digital Analytics world are familiar with what a landing page is and its significance. Wikipedia defines a Landing Page as “a single web page that appears in response to clicking on a search engine optimized search result or an online advertisement that is meant to convert site visitors into sales or leads”.  But another possibly under-utilized web marketing technique is the use of the actual Ads or what are called Mini-Sites as mini-landing pages. These are the advertisements that sells a websites Landing page!
It does not matter if your website has one page or hundreds, identifying and optimizing your landing page is vital to the success of your website. No matter the purpose, whether your site was written as a source of information or your goal is to generate sales, it is very important to accurately measure traffic on your site to isolate those pages that are ground zero for entrance to your website. After all what good is a website if it can’t draw in traffic and generate intended conversions? The Mini-Landing page or site just adds another measurable way to draw in visitors to a site. Mini-Landing pages are typically Ad based versus Mini-sites which contain significantly more information where “multiple pages are presented in a single navigable view, much like a traditional web site.” 
So what elements make a good text Ad or mini-Landing site? In general the mini-Landing page has very similar features to an actual Landing page just on a smaller more refined scale. In an article by Paras Chopra on the Search Engine Journal Website a mini-landing page ad should have the following elements to be most successful. 
Main Elements of a good Mini-Landing Page Ad
Clear Purpose and Direction
The mini-landing page should be very straight forward in its purpose and guide the visitor to the intended next location, which in this case, is your website’s landing page. It is however even more critical that the ad has a short, straight forward headline with no unnecessary fluff that may confuse or distract the visitor from the intended goal. It should quickly catch the reader’s attention with a key idea or offer that motivates a visitor to your website. Effective persuasion is the key here!
Catchy Text and Visuals
Customers reading your ad should be able to tell almost immediately what the purpose of the page is. It should be very plainly written and obvious. Any text should be clear and to the point, and properly sized and placed. Your visuals should quickly provide the reader with the knowledge of how your offer is relatable to them. 
Example of a mini-Landing page for provided by unbounce.com
Nothing sells better than a recommendation or positive feedback from another visitor. It helps to apply some measure of “social proof”  if possible that your website can deliver exactly what is being advertised. It can be in the form of trusted symbols establishing achievements or awards your website may have earned providing verifiable proof of a websites legitimacy and standards. Relevant text specifically indicating who the ad is intended for works well also. 
“Call to Action” 
Last but certainly not least is the request for the customer to actually click on the ad leading them to your website’s landing page.
Regardless of which technique is chosen to represent a website, either would be beneficial in providing additional track-able ways to generate traffic to your site.
Example of a mini-Landing site provided by heaventhemes.com
Checkout the following articles for more detailed information on creating a mini-Landing page Ad or Site.
How to Write a Killer AdWords Ad by Treating It a Mini Landing Page for a more detailed listing of the elements recommended for a great ad. 
Landing Pages or Mini-site? By Josiah Williams at Notationgroup.com for an interesting article on mini-sites.