That's a very broad topic you have initiated.
Not one easily addressed in an email.

It it made even more broad by the fact that you
have purchased one of the more powerful modeling
tools available, at least one that does not come
with break-the-bank pricing.

Though I have not used Erwin, I've been told it
is fairly comprehensive.  I have made extensive
use of Case 5 and Designer 2000 for database
modeling and design, also comprehensive tools.

There is a lot to consider:

Naming standards
Domains
Methodology

One thing I noticed was that developers would be
using the tool.  Do the developers know anything
about data modeling?

Data modeling is not about designing tables, it is
about modeling the data that is needed to supply
the correct data to an application.

Education in data modeling should be considered mandatory. 

Do the developers have interviewing skillls?  They will need them,
as they will need to interview the folks they are writing the app for,
and need to understand what the users really need. Which is not
necessarily the same as what they want.

When it comes to designing the database, do the developers
know the rules of normalization?  And not just the first 3 either,
but 4,5 and BCNF. 

Normalization is not as difficult as it first appears, but is extremely
important for maintaining accurate data, performance and reducing
the amount of code written to support the app.

You might like to point your browser at google to find articles at tdan.com

http://www.google.com/search?hl=en&q=data+modeling+site%3Atdan.com&btnG=Google+Search

Two of the best books on DM in my opinion:
http://www.amazon.com/gp/product/0201416964
http://www.amazon.com/gp/product/0932633293

I've rambled long enough, time for someone else to give it a shot.  :)