Bldg first permanent layout. How To Wire DCS.

Get Barry's book. That is the best suggestion you are going to get, and not just from me.

Definitely get Barry Browkowitz's book. It was incredibly helpful to me in wiring my first layout (I'm virtually done with the double main lines).  Furthermore, Barry is on this forum and I've found him to be a tremendous source of help.  

Having said that, if you plan to use turnouts on your layout and don't want to re-wire them or have them as the nexus point for three discrete track blocks, don't be disappointed, as this will make it virtually impossible to wire for DCS according to Hoyle.  As will using toggle switches. But the DCS is more robust than I expected despite all the criticisms out there and, while sometimes quirky, it hasn't been very problematic. 

My mains are approx 90-100' each and I star pattern wired, with the drop from each track block running to an MTH terminal block that is wired to the TIU. While probably overkill, I used 14 AWG for all track block wiring power drops. Having never done this before, I came to the conclusion that no one ever complains that their wiring is too robust. 

Any specific queries, feel free to ask and someone can help.  

Peter

Get the DCS O Gauge Companion (Barry's book). Everything you need to know is in there, with diagrams, sections of track per block, etc. I would also recommend using MTH terminal blocks and OGR wire, #14 to terminal blocks and #16 from term block to track feeders.