While it isn't always possible to obtain, advice that makes specific predictions is typically good. For instance, for fitness I've tried both Starting Strength (for exercise) and Lean Gains (for diet). They both made strong predictions about what would happen to you after doing their program for one to two months (Starting Strength: get substantially stronger; Lean Gains: lose a substantial amount of weight). For me personally, the Starting Strength predictions were accurate, but the Lean Gains one were not. So, I continue to do Starting Strength, but not Lean Gains.

In general, even if strong predictions are not made for you, you can translate advice into implicitly making such strong predictions. (This is, unfortunately, harder for things like planning for the future, when waiting to see if the predictions pan out is very expensive.)