Tax strategies w/o business license

[Maira Molina]

I’m reading tax strategies for the savvy real estate investor by Amanda Han and Matthew Macfarland. They briefly mention missing deductions on tax returns such as mileage driven to visit rental properties, meals with real estate agents, writing off portions of a trip as a business expense, purchasing technology as expense related etc. Can this be tax deductible if you do NOT have a business license in place? What is the preferred method when starting property rentals; have a business license or not?