Finding the right multifamily rental market

I'm curious to see what source types have provided the most value in terms of information/data when determining which market to invest in for multifamily investors of any level. As a new investor, it has become apparent that finding the right market is crucial and should be one of the first things determined in order to be successful. What types of information/data would you suggest to look for in order to determine the market good or bad and then what sources provide the best avenue to find that information.