1/8192 odds. That's it. It's all luck unless you manipulate the RNG.
I am sad to say that I have never found a Shiny in the wild in my entire Pokemon life. The only ones I've ever encountered were through cheating and through in-game events, like that Red Gyarados in SS, the shiny Gible in Black 2 after beating Benga, and the shiny Haxorus in Black 2 after completing the Unova Dex.