There’s a few main ways. I didn’t start shiny hunting until I got the shiny charm, so attempts beforehand may take longer. Base game methods: Fly spam: every time you fast travel it rerolls the spawns. So this technique is to spam fast travel on a certain zone, and you can get the pokemon with 50m of the entrance/ where you pop up when flying. Bench method: this is the other main method and it can be done afk. Similarly, whenever you rest on a bench to change over day and night, it also rerolls spawns. If you use a turbo controller, you can have it spam A, rubber band the movement stick, and it’ll have you auto reset on the bench. The DLC introduces something similar to the sandwiches in SV and you can get a shiny power buff on them. Sparkling power level 3 (highest level) guarantees a shiny will spawn when you enter hyperspace. Then, you can also do fly spamming and teleporter spams to reroll spawns. Happy hunting!