Start with the commercial objective
A channel budget only makes sense when the business outcome is clear. Define the audience, conversion event, sales capacity and decision window before assigning spend.
Budget for the whole system
Media cannot compensate for weak creative, slow landing pages or delayed follow-up. Treat production, technology, tracking and optimisation as part of the investment.
Create room to learn
Reserve a controlled portion for testing audiences, messages and formats. The goal is disciplined learning that improves the core plan.