It's by word of mouth. I've been in the same occupation for about 40 years. Incidentally, I forgot to mention, even though I wanted to emphasize this, that I am not a lobbyist. I'm a strategic communications and business development consultant. I've been doing this kind of work for about 40 years.
Over those 40 years, I have probably had a few hundred clients. I haven't been able to count them exactly. I have always worked for fees with all my clients. For some clients, I received fees plus a commission, but I have always received fees from all my clients.