As an external advisor I believe that concrete examples of how your knowledge can bring value to the company will get you far. Past deals and where you brought value. Even though a Google search for M&A will give you a huge number of hits, finding the information that is relevant for your company, this target, this history, this list of complexities etc. will be extremely difficult. What you bring as an advisor is knowledge about how to navigate complexity and a deep understanding of how to bring value from the given situation. If you are dealing with experiences companies/CXO’s you may also offer your services as a neutral sparring partner, being able to identify challenges and ask questions that other (for personal or political reasons) are either not able to see or willing to bring forward.