You don't list your bike....but here's how I did mine and it was a clean install.
I did like RoadCapt did and used the two capped wires that run to the headlight bulb plug inside the fairing, clean and powers up with ignition...\

what I also did because I use the Zumo on different bikes is I cut the hard wire approximately 10 inches from the GPS, installed a power connector ( looks like the Battery Tender plug) here. This allows me to quick disconnect the GPS and move it to another bike. I have a quick disconnect mounted on the other bike...easy stuff. I bought the quick disconnects at Car Quest, not expensive at all, around 5.00 each.

Run all the wires down the handle bar into the fairing through the clutch hole...I also ran the 3.5mm male to male AUX plug inside the fairing from the radio faceplate through the front brake cable and out the clutch hole to the GPS, wire tie all loose wires and you have a clean setup....

 

My unit is mounted on the left side, not right with a RAM mount, but I just pulled the front fairing (a 15 minute job once you're all set-up) and hardwired the connector to my cigarette lighter power. Works great, most of the wiring is hidden in the fairing and the rest I carefully wire-tired to the bar.

 

Standard mount and use the cig lighter...just wrap the cord around the handlebar once. It doesn't flop around or get in the way either
I considered hard wire but then the cradle would be on bike all the time.
I like the option of unplugging and taking the whole cradle sometimes for a piece of mind.

If hard wired...undo the thumb wheel and cut the wires ..them i'm SOL.
it's the thiefs that worry me

 

I spliced in a second cigarette lighter inside the fairing. Powers on with the key.

 

I bought a power cable that allows it to be wired to the battery, ran the wires under the gas tank.
Got a couple things wired to the battery, have to install a fuse block this winter to clean things up under the seat.

 

I use the Harley mount and wired it straight to my battery. That way the GPS doesn't shutoff every time I stop the bike to check a route or take a quick break.

 

Ram Mount and Powerlet. Clean and works like a charm.

 

I use a power outlet from Kuryakyn and it's wired into the headlight nacelle:

 

Powerlet Plus outlet;

 

I have the Tom Tom Rider 2. I put the RAM mount on the left handlebar, and routed the supplied wiring harness down the handlebar, then under the tank to beneath the seat. There I wired into the AUX power supply. This way I can switch the GPS on with the AUX switch on the inner fairing. Looks very clean. When I ride without the GPS, I just tuck the plug on the GPS end of the harness between the harness and handlebar between 2 wireties. Nearly invisible then.