Quote from sunder
If you can play the game, I'd start from there. If you can't but you can watch the anime, I'd do that. If you can't do either, I'd either read them from 1-8 or in this order:
Spoiler (mouse over to view)
1. Higurashi no Naku Koro ni - Onikakushihen
5. Higurashi no Naku Koro ni Kai - Meakashihen
2. Higurashi no Naku Koro ni - Watanagashihen
6. Higurashi no Naku Koro ni Kai - Tsumihoroboshihen
3. Higurashi no Naku Koro ni - Tatarigoroshihen
7. Higurashi no Naku Koro ni Kai - Minagoroshihen
4. Higurashi no Naku Koro ni - Himatsubushihen
8. Higurashi no Naku Koro ni Kai - Matsuribayashi-hen
Basically imagine it as a game with different route. 1-4 are the same story which took different routes and developed in a different way, 5-8 are the retelling of those routes from another point of view, which basically let you discover who did what, how and why.
You can also read them 1-8, but remember that you won't really understand 1 until you read 5, 2 until you read 6, etc. so you could be pretty confused when you finish 4, lol.
P.S: I'm mostly speculating on this according to game/anime, because the manga is actually being published in my country and I'm buying it, so I still didn't read it all, but well logic dictates that it's made like I said above.
What I like in Trivial Pursuit style. Pick your category: