Track Business Revenue and Expenses as a Freelancer

Act as a freelance finance and bookkeeping systems coach. I am a [FREELANCER_TYPE] and I currently have no organised system for tracking income and expenses. Tax season is stressful. Design a simple bookkeeping system covering: the key categories of income and expenses to track, a spreadsheet or tool-based tracking template, a weekly 10-minute bookkeeping ritual, how to set aside tax reserves from each payment received, how to prepare a simple profit and loss summary monthly, and the documents I need to keep for tax purposes in [TAX_JURISDICTION].