Made offer on fourplex - how to negotiate?

[Ernad D.]

Dear BP community,

I just made an offer on a fourplex and am looking for negotiation advice.  The property is in really good shape and had a new roof done on 2014.  The area is a B- neighborhood so it will not be too difficult to find tenants but the appreciation will be minimal.  The seller listed it at $170,000 and I just made an initial offer of $144,000.  

How do I negotiate once the seller counters?  In what amount increments?  What amount should I set as my max offer?  Any other advice?  Please see the following for more details.