If you are flipping houses the local "months supply of inventory" (MSI) seems to be the one that we get the most use out of. When this number is increasing that means that either more houses are coming on market (competition) or the buyers are not as active (market slowing down). For us anything less than 4 months is pretty bullish and we will buy just about any deal that meets our minimum requirements if we can flip it within a month or two. 4-6 months MSI we take a second look and only pick houses that are really safe and quick 1 month flips. Anything over 6 months and we stick with the low-end starter home properties and flips that we can market to rental property investors. The buyers really start drying up with a high MSI and you can end up sitting on even nice houses for a long time.
If you are a buy and hold investor for rentals we usually save cash or do flips when the MSI is low and when it gets higher we start looking for prices to drop and that is the time to start picking up rental properties for the long term.
I have looked at many different indicators, price change, sales volume, etc. but none of them really seem to correlate to performance for a property better than MSI. Just remember that it is a lagging indicator and like most of them, it goes up faster than it comes down.
I do not worry about any national indicators since they really do not apply to my local market.