Instead of MS Excel, if you use MS Access, the data can be analysed easily. Secondly, your company should start using some CRM software like ACT Sage. These softwares have integration with MS Outlook or Outlook Express as well.
Coming to solution to your query, analyse the data in the following manner:
a) No of visits by the customers per month
b) No of purchases made by the customers per month
c) Customers make what type of purchases - MIS based on product
d) MIS based on geographical spread of your customers
e) MIS based on the type of customers - individual, corporate, family etc
To find out a particular customer is a regular customer, quarterly customer or yearly customer, you can issue the cards to the customers. All the purchases made by the customers can be registered under this customer ID No. This will solve your query.
By the way, I am into soft skills, behavioural and management training. Your query pertains to my subject module "Monitoring Employee and Business Performance". This training module is quite important for the senior management personnel.
To make you aware of my training activities, I have attached my Training e-Brochure to this post. You may recommend training of your senior managers on the subject module mentioned above.
Dinesh V Divekar
Management & Behavioural Training Consultant
Limit of your words is limit of your world[I][COLOR=#0000BF][COLOR=#FF0000]
4th April 2010 From India, Bangalore