There’s no sure-fire path to success on Amazon or online in general. Every road to sales takes constant research, testing and tweaking. Retail arbitrage is something that lots of small Amazon sellers do successfully, but every product is a unique challenge. It takes knowing how to research and buy profitably day after day. A good product scanning scouting app is a must. Are you using one? Private label requires upfront costs, but if you can build a brand off Amazon using a blog and social media, you can drive buyers to your Amazon products instead of just waiting for Amazon shoppers to find products. Dropshipping can work but you need to really research your suppliers and make sure that at the end of the day, you’re left with a profit.
Sorry I don’t have a 1-2-3 roadmap for you. Every sellers path to success is little different.