To write a compelling ad you will want to make it as relevant as possible to your selected keywords. Your ad will be more successful if it matches or relates closely to the keywords that you associated with that ad.
Include a CTA (Call To Action) phrase in the description lines and consider including a unique value proposition. This will help the potential customer become involved and desire to learn more about the product.
Do not use the word “ad”, “headline”, or "Click here" anywhere in your ad because this will give you poor results.