A model is not for decoration — it answers questions: what a customer costs, when hiring pays back, which price survives a discount.
Sheet 1. Inputs
Price, average order value, conversion, traffic cost, salaries, fixed costs. Keep every parameter in one place so you change them in one place.
Sheet 2. Unit economics
Revenue per customer, variable costs, margin, CAC, LTV and payback period. This sheet shows whether a channel works at all.
Sheet 3. 12-month plan
Month by month: customers, revenue, costs, cash flow. No «average growth» — explicit assumptions per channel.
Sheet 4. Scenarios
Pessimistic, base and optimistic. One switch recalculates everything — handy for testing decisions before they cost money.
That is enough to make decisions without building «corporate BI» on day one.