nix the checkride prep from King Schools... I got it and it wasn't as big of a help as my instructor was. And I think some DPE's are on to what John and Martha teach and can tell when you've prepared with that material. Then they have fun handing you rope until you hang yourself.
But the written prep info from them was good. Helped explain many concepts.
I also used Sheppard and the ASA products for the written. Just knuckled down, studied for several days straight with those products, then took the test.
For textbooks, the ones that Wallboy mentioned should be in your library. And I'll add Bob Gardner's "The Complete Advanced Pilot" and "Instrument Flight Training Manual" by Peter Dogan.
And look at you go,
@CC268, a year ago you were asking questions about your medical... and now you're cruising cross country, making low passes, and chasing your instrument rating!