They recommend starting at the beginning and going chronologically.
Dianetics then sos.
Dianetics is more of a tech manual and sos a how to guide.
If you only read one, read sos.
I've read nearly everything publicly available in print.

Before i got to stss.nl i saw that some people would never understand.
If you won't figure out your problem, no amount of books is gonna help.

I found a big one of mine, i thought violence was an acceptable means to my ends.

Let me know what you think over time.
I've not known enough folks to do a thorough test of the claims.
It does find adherents that give their last dollar to read ron's work product.
Alot of religions do.