Low Voltage System wiring (5-24VDC), Rules of Thumb? 1

I don't know of any references like you're asking about. I assume by "surprises" you are looking for safety-related information related to wiring. Here are some things to keep in mind:

Is your power supply for each voltage current-limiting? If so, at what current?

What size wires are you using for power wiring? How did you calculate their values?

Do you have overcurrent protection, e.g., fuses, protecting all ungrounded power wires? Is it needed? If so, what types and sizes for each device? How did you calculate their values? Do they provide selective coordination, i.e., will the one closest to a fault actuate first?

Do you have an adequate ground connection to any exposed metal components such that there is a low impedance path back to the power supply that will allow the appropriate overcurrent protection device to actuate in the event of a fault to ground? This includes any 120 V circuit wiring that may provide power to any low voltage power supplies, meaning a three-wire cord with a grounding plug unless the equipment is double-insulated.

Is there adequate heat removal for all components, including the wiring?

Those voltages are not life-threatening. However, it would be good practice to use finger-safe wiring terminals for power wiring. Cover exposed wires with heat shrink tubing if necessary.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

Fork or ring 'crimp' terminals are usually used on stranded wire for terminating on screw terminals.

There are also crimp ferrules for stranded wire, that helps prevent a wild strand from causing problems.

Wire nuts are considered poor practice.