Two businesses, two event models

Northfield sells appointments to sit in a used car. First-wave events: view_item when a vehicle-detail page (VDP) loads (item_id, item_name, price, item_category); form_start when the sales-appointment form is opened; generate_lead only after a unique sales-appointment thank-you (lead_type=sales_appointment, form_id); click_to_call on the tel: link (link_url, page_location); schedule if a real scheduler exists. Do not fire generate_lead on page_view, newsletter signup, chat-widget open, or “contact us” if that form is not a booking. Cedar & Stone sells a dispatch: a tech on a driveway. First-wave events: click_to_call (most of her demand is the phone); generate_lead or form_submit only on a unique thank-you, with service_type of tuneup, estimate, or emergency_heat; book_estimate if she adds an online estimator; book_tuneup if the $129 fall plan can be reserved online. view_item on a VDP is the wrong primary conversion for Priya. begin_checkout for a VIN is the wrong primary conversion for Dana if nobody can check out a car online.

An event without parameters is a count you cannot debug. On generate_lead / form_submit send: form_id or form_name (sales-appt vs newsletter vs “ask a question”); lead_type or service_type (sales_appointment, trade_in, tuneup, estimate, emergency_heat); page_location (which URL actually converted); and a unique event_id or transaction_id so GTM/GA4 can dedupe a double fire. Optional and honest: value only if you have a real ticket or a written estimate — do not invent $18,400 because that is Northfield’s average asking price. On click_to_call send link_url and page_location so you know whether the tap was the sticky bar, the GBP embed, or the footer. On view_item send the VIN or stock number as item_id. If two forms share one thank-you and you do not send form_id, both look like the same lead.

Three common lies, all of which will train Smart Bidding toward noise. (1) The tag fires on page_view or on every session — “leads” equal sessions. (2) The tag fires on form_start or on the first field focus — you are counting intent to type, not a submit. (3) Two actions share one destination: newsletter and sales form both redirect to /thank-you, or a chat open and a booking use the same custom event name. A fourth lie for phone shops: the number is displayed (or copied) and you count generate_lead, but nobody tapped tel: and no call-tracking number logged the ring. If Dana optimizes Google Ads to generate_lead while that event is the newsletter, CTR and “conversions” can both rise while Saturday’s desk stays empty.