I do not recommend using global variables to pass information between one procedure and the next. That is what Procedure Parameters are for. It is too easy to introduce very hard to find bugs when using variables to pass data.
Global Constants are an entirely different subject. They will help prevent typos and make it very easy to maintain your code base when, for example, company information changes.
Const CompPublicPhNum As String = "(800) 555-1212"
Const CompPresidentName As String = "Superman"
Const CompAddress As String = "1 Broadway, Ste 1"
'Etc
In fact, all business rules should be kept as constants in one location.
My general rule is that it is far better to type "Dim Something As String" 100 times, than to have it left with a value from some other sub even once a year.