The best way to be sure about your bags authenticity is having it professionally authenticated by Louis Vuitton. But if you haven't got the opportunity to visit a Louis Vuitton store to have your bag authenticated, or just want pointers when looking to purchase a vintage or second hand Louis Vuitton bag (online or in store), there is a lot of aspects of the bag that you can check yourself.
Luxity.co authenticates hundreds of Louis Vuitton handbags every month and shares some really valuable insights regarding how to authenticate Louis Vuitton bags. Like counting the stitches on the handle tabs, checking the date codes, brand stamps and hardware.
Vintage Heirloom has created a video showing you in detail how to find the signs of a fake Louis Vuitton bag. I have used it to help authenticate bags I felt a little iffy about.
Emma Anders has a great video on how to spot a fake and appreciate Louis Vuitton Canvas Bags.