Accounting/Book keeping for a beginner

I’m interested in selling on Amazon. I’m currently a complete beginner and have incurred zero expenses so far.

What do I need to keep a track of specifically and how many spreadsheets should I have?

What is the best balance of keeping costs low/investing in software for a starter? (I plan on starting with £1000 to invest).

What are the best resources/guides to learn about accounting for a beginner?