Hi @Scrumpto
Personally, I’ve created a project named CLIENT CONTACT.
each task is a named "client name | department "where I do have custom fields for POSITION, EMAIL, PHONE, COMPANY NAME…
I do sort this project by client company name and show in the main page all of the fields that I want to filter quickly. For more complicated search , I do use advances search, which is really interesting.
To link my tasks to client contact, I do use “@contactname” in the description or comment sections. As my contact name is a task, Asana create a hyperlink. When you click on it you directly have access to your contact info.
Hope this help!
Regards