The only person I have converted to coasterism is my partner.
When he and I got together I am pretty sure the average GP person knew more about roller coasters, and theme parks than he did. However, many years later he is VERY knowledgeable about parks. I started him out slowly by showing him the way to tells different coaster companies apart and such, and know he knows the name of each element, and what new coasters are coming next year, and so forth.
I'm very thankful that he actually enjoys theme parks as much as I do, and that we can share such an awesome hobby together.