In any business the customer enquiry book or note-book is the most important
record to be maintained from a business point of view.
Alas, not many businesses give enough attention to this simple documentation.
It need be elaborate.
I used to buy 80 pages note-books and allot half-a-page (or sometimes a full page)
for each customer/client.
The details contained it it:
Sl. No. 555 (This is the serial number of the enquiry)
Name: Mr. John or ABC company
Phone No. cell no.
(On the left hand side margin, I write how the enquiry was generated: e.g. Walk-in, telephonic, regular customer, etc.)
In case the enquiry is converted into sale, then it can be crossed with two red lines (or whatever) with narration: closed. Sometime: Lost. So that at any point of time we know which are the live enquiries.
An index in the first one or two pages will be of great help.
Follow this procedure and prosper!