Most merchants look at one number: sales. It is the least useful one, because it is an outcome rather than a cause.
1. Conversion rate
How many visitors become orders. If traffic rises and sales stay flat, the problem is the store, not the marketing. This number tells you where to spend: on attracting visitors or on fixing pages.
2. Average order value
Raising it is far cheaper than acquiring new customers. Watch it after every change to offers, recommendations or your free-shipping threshold.
3. Cart abandonment rate
A sudden rise usually means a technical fault: a payment method stopped working, or shipping is miscalculating. Watch this daily, not monthly.
4. Most-viewed versus best-selling products
A product viewed often but rarely bought has a specific problem: price, images, description, or sold-out sizes. This is the fastest improvement opportunity in your store.
5. Traffic source
Where buyers come from — not where the most visitors come from. A channel bringing a hundred visitors of whom five buy beats one bringing a thousand with no orders.
How to read them
Compare with the same period last month, not with yesterday. Single-day movement is noise; the four-week trend is the signal.