Adding a follow up date in Business Contacts Manager

I need to add a user defined field (from field chooser) that allows me to
assign a specific date(s) to each opportunity or account company. I'm in the
insurance business, and we follow up with potential customers based on the
renewal date of their policies.

Is there any way to do this? Using field chooser, I was able to create a
column in my current view for "renewal date", but doing so doesn't create the
field inside Business Contacts, so the field simply shows "none" for data.

Anybody out there who knows how to deal with this.

Thanks