The oldest and simplest type of lease, the flat lease sets a single price for a definite period of time. It generally is the best deal for the tenant but is becoming increasingly harder to find. (Caution: Avoid a flat lease if the term is too short; a series of short-term flat leases could cost you more in the long run than a longer term with reasonable escalation clauses.)

Excerpted from Start Your Own Business: The Only Start-Up Guide You'll Ever Need