I'm very interested in starting out house-hacking by buying a duplex—hopefully I can make it happen in or around the Denver market (that is incredibly intimidating for a newbie!). 

Financially this is not a good investment approach as it seriously reduces your ROI.

As an investor you give up some return in exchange for that passive approach but it depends on how much time you have to commit to it.Here is what I have learned over the years. 

If it sounds like a good deal lock it up, check the appraised value first and then approach people for advice

I agree that FB ads may be a good idea and Jake nailed it with the wait and see approach.

@Quincy Miranda the approach that @Caleb Heimsoth describe is how to find the value of a multifamily. 

I recently lost a deal to another investor despite being in touch with the decision maker and having a tentative date set to tour the property.My approach this past year has been very direct to the point.

Colleagues of mine have used this approach after financing a property under their name.

Do you approach Freddie directly somehow or through a loan officer? 

Using this approach will help you find the realtors who are actively listing in your area.