How to Negotiate a Lease It's a buyer's market for commercial space, and landlords are offering huge concessions to new tenants--but you won't get a nickel unless you know what to ask for.

This year may be the best time ever to rent space to start your own business: The nation's 102,000 shopping centers are dotted with vacancies that landlords are desperate to fill. "I've never seen better deals," says Paul G.W. Fetscher, president of Great American Brokerage in Long Beach, N.Y. "Everything is negotiable."

But knowing what to negotiate is surprisingly complicated. Landlords may be anxious to fill empty spaces, but they're also eager to make up for the money they've lost during the recession, and, unless you're careful, that bargain lease you sign today can be filled with hidden charges, escalating fees and clauses that kick in when you'd least expect it.

Nick Rizzi, a former New York banker, thought he knew a lot about leases when he rented space for his tax preparation business, Smart Tax, in Brooklyn five years ago.