It's too difficult to put this list in chronological order since the books span multiple decades. The book Fall of Reach for example begins in 2535, jumping back to events before 2517 and ends in 2551 just before Halo CE begins.
Ghost of Onyx begins at 2545, jumps back to 2531 and finishes around 2552 (Part of Halo 2 & Halo 3) for example.
Halo lore dates back to before 100,000 B.C.E.
http://halo.wikia.com/wiki/Timeline
Even Forerunner's had their "gods" or erm, Forerunners.
http://halo.wikia.com/wiki/Precursor
The Precursor's are to the Forerunners as the Forerunners are to Humanity.
The games are somewhat easier to date. http://halo.wikia.com/wiki/2552
- Halo Wars: 2531
- Halo Reach: 2551-2552?
- Halo: CE: 2552
- Halo 2: 2552
- Halo: ODST: 2552
- Halo 3: 2552 - 2553 (Memorial)
It doesn't matter which book you should read first but I'd just read them in the order they came out.
Halo: The Fall of Reach (Great book with the Spartan II project and lives of the Spartans and the Fall of Reach)
Halo: The Flood (More in-depth Halo CE story)
Halo: First Strike (Bridges gap between Halo CE and Halo 2)
Halo: Ghosts of Onyx (completely seperate story which features the Spartan III project)
Halo: Contact Harvest (Based on first contact with Covenant with Sergent Johnson taking the helm)
Halo: Cole Protocol
I'd read Halo: The Fall of Reach and Halo: Ghosts of Onyx if you plan on buying Halo Reach for more than the multiplayer.