Without analytics, you’re guessing which products, traffic sources, and pages actually drive sales. Setup steps:

1. Create a GA4 property at analytics.google.com and generate your Measurement ID (starts with G-).
2. Add the GA4 tracking snippet to your store — Shopify has a direct integration field in its settings; WooCommerce typically uses a plugin (e.g. Site Kit by Google) to avoid manually editing theme files.
3. Enable Enhanced Ecommerce tracking, which captures specific events: view_item, add_to_cart, begin_checkout, and purchase — this is what lets you see exactly where in the funnel customers are dropping off.
4. Set up a Conversion marked on the purchase event specifically, so your ad platforms (if you run paid traffic) can optimize toward actual sales, not just clicks.

Check back after a few days of traffic and look specifically at the funnel drop-off between add_to_cart and purchase — a large drop here often points to a checkout/payment friction problem worth fixing before spending more on traffic.