The layout is DCC so I need a power bus. I always do this by laying down some self adhesive copper tape. I am also using Tam Valley Frog Juicers to control the polarity of the frogs - I use Peco Code 83 Electrofrogs.
I am wiring up the first board. The railroad is designed so that it can be dismantled (we live in a rented apartment so who knows?) so the track is all connected across the board edges with short removable lengths of track (no points cross the edges at all). As I only have two 6 pack Frog Juicers (for a total of twelve points) I have to accommodate those connections across the boards as well.
I am terminating the wiring into strip connectors as, once the layout is back together, the joins will be permanent (until and if we move).
The two power busses are connected to the track via the green and yellow drop wires whilst the frogs are connected by the black wires. The black wires will connect to the Frog Juicers on the middle board. There is a staging yard coming off the other end that will have a single point, hence the ongoing green/yellow and black connections.