The single biggest source of lost deductions is unphotographed paper receipts. Snap them as soon as you get them.
Glo Invoice has a native receipt scanner that pulls vendor, date, and amount automatically. Categorize as Materials, Tools, Mileage, Subcontractor, etc., and tie expenses to specific jobs for true job costing.
Year-end P&L reports break expenses by category so your accountant has clean data.