First Commercial Deal - Small Office Building, worth pursing?

[Dan Frank]

I currently own 10 properties on the residential side and have an opportunity to acquire a small 3-unit office building that is fully leased.  This would be a contract for deed with a family member that owns the building free and clear.  Not sure yet on what the terms would be, but the purchase price would be around $300k and gross rents are $3,300/mo.  Taxes are somewhat high at $11k annually but it's still a decent return if I can put 10-15% down.

Since I'm new to the commercial side, is there anything I should look out for here?  Figure this might be a great way to diversify the portfolio, but want to do my due diligence since I'm new to the commercial side.

Thanks in advance!