1. Long tail queries will bring targeted traffic because the FAQs will be relevant to the searcher’s query 
  2. Add CTA :     by adding a CTA close by you can lead visitors to key conversion.
  3. Add Internal Links to topic based answers: by adding a link in the FAQ to a product or service page, 
    you can drive visitors towards pages with more detail about the product or service offered. 
    You should link every solution and the whole FAQ section back to your landing page, contact section, or to your online store.

  4. Transparent: If you earn the trust and loyalty of a visitor they are more likely to make a purchase 

  Source: http://www.webceo.com/blog/answer-user-questions-wisely-how-your-FAQ-section-will-increase-conversions/