To develop some knowledge before touring your first empty box, read up on the basics.
Repeat after us: Leases are supposed to be negotiated. Every detail is up for grabs, from price per square foot to tenant improvements.
Negotiate Your Commercial Lease (Self-Counsel Press) by Dale R. Willerton is a how-to manual with plenty of information on getting yourself a good deal on the right office space.
"How To Negotiate A Lease" by Jan Norman from March 1998 Business Start-Ups.