The main thing: make sure any powered wires get their power through a fuse somewhere. This is vital, especially if you have not wired a vehicle before, as road vibration can chew through the wire insulation in a week, making a short. If that happens, the power needs to go away, or else the bike might!
The wire you send to a switch and the wire that carries that power away from it (or the device it powers) must be the same size, or else the return wire (to ground) bigger. There is equal current in both of those wires: it doesn't go anywhere else. The wire from the switch, then out of that switch to the device, must be large enough to carry the current on a 150 degree day, because it can get that hot on the bike.
Generally speaking, the smallest wire you should use on a bike, to power anything but the starter, should not be smaller than 20 AWG size with the exception of LEDs or the little lightbulbs in the instruments: those can work fine with 24 AWG or 22 AWG size, for both the wire to, and from, the device. The coils need NO LESS than 22 AWG power wires to & from them them: 18 or 20 AWG is better. For the headlight: check the wattage of it, then divide that number by 12 (volts) to find the current, and size accordingly: the typical 60 AWG headlight then uses [60 / 12] = 5 amps: all 3 wires to it must be at least 20 AWG for this much current, and 18 AWG will make it last longer and run cooler.
The frame makes a poor ground (ask any Harley or vintage British bike rider about that...) but it also MUST be grounded or the sparkplugs won't work very well. Battery Ground must go to the top left rear engine bolster on the 750 for best results, in between the engine and the frame, with both cleaned of paint at that site.
When I wire a [semi] custom bike, I make all the Green Ground wires 16 AWG because that is nearly 150% of their needed value, and everything works better for it. Then the feeder wires to every/any thing can be smaller, and you'll be in good shape in any situation.
