Panel and wiring
I tend to agree with the point of doing your own panel and wiring. After learning sheet metal work, fibreglass, hardware, engine install etc why not the electrical too? Great knowing how it all went together. I think the most difficult part is the planning due to all the choices required...VFR or IFR, glass or steam (and if glass which brand?), how much redundancy, breakers, fuses or VPX etc etc. It is not a hard job but it is tedious and time consuming. The Aeroelectric Connection book gives great info and sample wiring schematics as do other aircraft wiring books. If you can read the electrical schematics for your selected equipment you can wire it up. I know I did on mine and knew nothing about it to start. Everything else you need to know is on the net and you may have an electrical guru on the field to ask for help. It's certainly a great feeling turning on the master for the first time and lighting things up!