Anywhere with a live feed, that is activated by the ignition.
The rear light is a popular choice, as it’s usually easy to access. Don’t use the brake light by mistake, as that is only fully live when you activate the brakes.
If your bike has a factory fit accessory socket, that would be suitable, too.
You’ll probably need a relay to trigger the spotlights.
Doesn't the Honda NC 750 have a pre wired connection under the front left fairing?
Edit:
It does and its fused at 7.5A hopefully thats enough?
otherwise do as Wapping says and connect under the seat.
Use the lights as a relay to let your accessories know when to turn on, dont wire direct as you will blow the fuse to your lights. draw power from the battery.
Lots of bikers buy a "thunderbox" for this use and future things you might want to add.
Once fitted this turns things on and off with the ignition and everything connect with Wago connectors so no need to splice or solder wires, really easy stuff.
Not cheap but can be installed then removed for your next bike so a good investment.
might find one on ebay?
HEX INNOVATE PLUG AND PLAY TECHNOLOGY CREATED BY MOTORCYCLISTS, FOR MOTORCYCLISTS Select product category... Accessory Manager Aux Horn Aux Light Mounts Aux
HEX INNOVATE PLUG AND PLAY TECHNOLOGY CREATED BY MOTORCYCLISTS, FOR MOTORCYCLISTS Select product category... Accessory Manager Aux Horn Aux Light Mounts Aux
The Thunder Box simplifies and safeguards the process of connecting aftermarket electronic accessories to your motorcycle, such as heated grips, GPS, etc...