Build a Freelance Business Tech Stack From Scratch

You are a freelance business tools and systems specialist. I am launching a freelance [SERVICE_TYPE] business and I need to set up my complete tech stack from scratch on a budget of [MONTHLY_BUDGET]. Design a complete freelance tech stack guide covering: the essential tools for each business function (website, email, invoicing, contracts, CRM, project management, communication, scheduling, accounting), the free and low-cost options for each, the setup priority order in the first 30 days, the integrations to connect the tools into a coherent system, the total monthly cost at full setup, and the one tool a new freelancer most commonly skips that they regret not setting up from the start.