Find an official Chinese brand web site and they usually have a link to their shop on Ali. For example, you want to buy some eSun filament for your 3D printer. You go to their web site www.esun3d.com/pla-pro-product/ and BOOM! Ali link!
Sometimes they don’t have a link on their web site, so you search for a brand on Ali directly and search for a gold rated shop with loads of followers and a properly maintained product catalogue. Here’s an example m.aliexpress.com/store/5793617?trace=store2mobile…