The V5 brain has 3 different types of ports - 20 motor ports (labeled ports 1-21), a single radio port (port 21), and 8 3-pin analog sensor ports (labeled ports A-H). These analog ports support 3-pin cortex-era sensors and (although not competition legal) 393 3-pin motors.
Wiring from sensors/motors to brain ports is relatively simple compared to the legacy cortex system. Here's some tips when doing so -
Keep wires tight around robot arms to prevent loose wires getting snagged on other robots or other subsystems.
Also, try to keep loose wires or wiring away from joints to prevent wires from being crushed by them.
Zip/Cable ties are a good option for keeping wires organized.
Wire lengths should be based on the maximum length that it needs to prevent wires from being stretched out by the robot itself.
You can do this by putting your robot to its full length before wiring.
Labeling wires with their port numbers helps to keep wires organized in the case they need to replaced or moved around.
Also, be sure that your robot has enough room so that the V5 brain screen and button are easily accessible and visible. The battery should be in a firm spot that is easy to remove and replace in competition environments.
Wire crimping allows teams to produce custom wire lengths and replace broken wires or wire heads. However, they can be to blame for dead ports if done incorrectly.
Here is the VEX Guide on Wire Crimping.