Know what a number can tell you.
Metrics are useful when their definitions are clear. A visit, a lead and a sale represent different stages, and a change in one does not automatically explain a change in another.
Keep comparisons fair
Write down the period, source and collection method. Note tracking changes, missing data and unusual events. Treat attribution as a model with limitations rather than a complete record of cause and effect.
A useful starting point
Write a short note describing your situation, the question you are trying to answer and the evidence you have. Keep it specific enough that someone else can understand the decision without guessing.