I wanted to get in the game with the least amount of risk of spending money so I figured out an approach that could get you started with no money. It's basically Retail Arbitrage, but without the stress of paying for the product first.
I got a square up account as my payment gateway and synced it to my woocommerce website. I then figured out a niche to base some products around that are well made and with consistent inventory that source from eBay and Amazon, but with same day or next day shipping.
Now my problem was I didn't want to use my money and then get stuck with any product that could be returned, this is where square comes in. They have an instant pay feature where if a customer buys from you store you can then do an instant payout to your debit to then purchase the product. Of course, this is minus your markup and credit card fees.
As for returns I use the sellers terms they provide, so it's usually anything by Amazon prime since they are good about returns, in addition, I just tell the customer there is a restocking fee of $5 bucks to cover the charge back.