[Osiris12345]

I'd say go to Shouso Strip first. It was my first Ringo album and I think it's a great way to get into her. It has a little bit of that quirk (Yokushitsu, Benkai Debussy, and Stoicism definitely come to mind) that KSK does but don't expect it in spades. Shouso Strip is more or less a rock album with some experimental tracks. It also has some of her most famous songs. Gibs, Yokushitsu, Tsumi to Batsu, Identity, Yami ni Furu Ame, Honnou, and Izonshou have all pretty much become iconic Shiina Ringo. Think of Shouso Strip as a way of getting to hear Shiina Ringo's real breakout into the mainstream. As an album, it also doesn't seem to have as tight a concept as KSK so I find myself listening to a lot of the individual songs from it. And that's really its strong point. It has some really nice songs that can stand on their own. It loses a little bit of momentum in the second half but really picks up with Honnou and Izonshou. Honnou is practically worth the price of admission alone. Definitely recommended.

Going to Muzai Moratorium, as has been previously said, is a pretty huge jump. It's definitely her poppiest album but the melodies from it are pop perfection so if you can handle more straightforward arrangements then you'll probably like it. I also find that her vocals take the most getting used to on this one. But it's really a great album. It's also the home of her big concert staple: Marunouchi Sadistic.

Heisei Fuuzoku is more or less a reimagined version of old Shiina Ringo songs with orchestral arrangements, containing 5 from KSK. It's good but only has 4 completely new songs. I'd recommend it if you're interested in hearing a different take on some KSK tracks and want to hear the jazz/orchestral side of Ringo. kuro_neko may be right by saying that this is a good step to go to after KSK but I would say whatever you choose, pick Muzai Moratorium last.

So I would say Shouso Strip --> Heisei Fuuzoku --> Muzai Moratorium.