How to handle utilities

[Ray Young]

I just purchased a home with a finished basement and two separate entrances.  I plan on doing a long term rental on the top and a midterm rental on the bottom.  I am currently paying the utilities and need guidance on how to structure the utilities for the tenants.

My idea is to do a flat rate to the long term tenant and have a clause for overage.  The midterm renter would have included utilities.  

I plan on putting in separate meters in a year or so.