Cap Rates and Gross Rent Multipliers

[Sippy Hira]

I'm trying to get my head around cap rates and gross rent multipliers.  I have a basic understanding of both, however, I've been told that for multi-family properties, I should pay more attention to the gross rent multiplier than cap rates.  Any advice on how to best evaluate if a duplex, tri or any multi family is worth investing in? What are the key financial metrics we should be looking at? Also, is a high or low cap rate better when reviewing properties?  Where just starting out in this space and doing our best to learn, but feeling a little overwhelmed with all of this information.  All advice is welcome!