A very good strategy is to start dropshipping in a niche to see if there is traffic, buying patterns. Once you start getting sales, cherry pick the items that are selling well, and buy those items wholesale. It's essentially the way Amazon does their business. All of Amazon's 3rd party sellers are basically dropshippers for Amazon. Amazon has all the sales data from all those sellers. Once they see something is selling well, they just contact the manufacturer and start selling the items themselves. I've seen it happen with MANY items that used to sell well for us on Amazon.