Before we can create Content Types, we need to define all of the individual Site Columns that will appear (ultimately) in our SharePoint lists. First, please look at the rather extensive set of Site Columns you get "out-of-the-box" and please feel free to reuse them instead of duplicating something similar.
The Site Columns available will depend first on the version of SharePoint you have available - Foundation, Standard, or Enterprise. Secondly, on which features (Standard, Enterprise, and Publishing) are enabled at the Site Collection and Site level.
In our case, we will be defining a document library to hold our proposals. We are going to define the following additional Site Columns that we require: