I believe the better ‘advertising’ is made by your own customers through reviews, whether on social media, app stores or rating sites like Trust Pilot, because it says more about the quality of your work and inspires confidence in who is looking for a broker. So, in this case, I think customer service is a priority because as we say in my home country, a satisfied customer comments with two friends about it, but a dissatisfied makes his criticism for about ten.
In addition, I think social media is a more accessible path and with the differential of the company can effectively communicate with its customers or potential customers