Don't be mistaken once you see "24" effects in your game menu - instructions counts as an effect too, so you have to have "25" effects. It's a common mistake among new players getting "all 24 effects" and then being unable to complete the game, because they forgot one more effect somewhere.
Another and more general advice would be to go blind and explore on your own as much as you can and gather as much effects as you can find. Like
>>10454 said, have patience and be curious. Once you start to feel like you have explored everything and/or can't find any more effects - you can check the wiki page and complete the game with it's help.
Play alone in a dark room with headphones on and the game unwrapped in full screen for more atmospheric experience.
You can either download the game from here or Steam page. The only difference between the two versions are translation of some effect names.
Don't play the game in so-called "multiplayer". Multiplayer is for pookies.
