Before starting to sell on Amazon, think about your current areas of expertise.

What do you know a lot about? Musical instruments? Fishing equipment? Electronics?

Figure out your niche, and use your years of experience in a particular category to find items to sell where you can add value.

Go to trade shows, especially those in Las Vegas.

Others here know more about doing this, and may comment.

Sell via merchant fulfillment before doing FBA to make sure what you are selling has a viable market.

Go through Amazon's Seller University thoroughly to make sure you understand the rules of this marketplace, especially the parts about legitimate suppliers.

Alibaba is NOT an acceptable supplier, nor is Costco, Sam's Club, Nike online, Walmart, CVS or any other retailer.

Learn the difference between a receipt for a retail sale, and an invoice, for a wholesale sale.

Visit the seller forums often, and ask questions. The rules for Amazon sellers can change quite often. Do not be caught unaware.

There are a lot of us who can be of help to you here, as you build your business, but you must follow the rules,

Doing so will help keep you from making errors that might get your Amazon seller account cancelled. You get ONE Amazon seller account per lifetime and there are no do-overs.