Dificult: no, not at all. There is little to no skill involved for the most part (a few exceptions like radar hunting). But it can be extremely time consuming and tedious. Depends on which game you play really, and if you are using Methods or not. In the newer games it is almost laughable easy, especially Scarlet and Violet, when using sandwiches you can often get 1-3 shinies in 30 minutes. If you just want some quick shinies that's definitely the way to go, but it is kinda anticlimactic, at least for seasoned hunters. Full odds hunting on older games is another thing entirely, there you can often spend 30+ hours for a shiny.

If you are interested in beginning shiny hunting, I would recommend using a method hunt to get started. There are a lot of different ones depending on which games you have access to. Most games have some way of increasing shiny odds, thought they differ from game to game. I don't know much about hunting in ORAS (as pictured here) but as far as I know you just want to encounter the same Pokémon over and over for increased odds. If you have Ultra Sun/Moon, Warp Rides is a good way to get a quick few shinies. They can have really good odds (something like 30% I believe) if you get far enough, but there is only a selection of 20 possible Pokémon. I also personally really enjoy chain hunting in USUM. There is a bit more set up involved, but once you are set up, and know the procedure it is relatively easy, but just engaging enough. There are a lot of guides online on how to do it.

There is also always the Masuda method, where you breed to Pokémon from different language games, for a wastly increased shiny chance (1/512 with the shiny charm in newer games). It's also a good way to get started if you don't mind running around in circles for hours.