How do you wire it so that it isnt on all the time?
I did a little more to my wiring than perhaps most people would
First, I tapped a wire that is simply the "on" wire from the ignition. That runs to a relay's switching coil, so when the bike turns on it flips the coil for the relay.
I used a 30a relay, and a line from the battery goes to that then to a small terminal block. If you can find an insulated bus bar or similar you can use that as well. In my case I couldn't, and so I ran wire loops on one side of the terminal block to make it all connected. If I want to add a new device I just have to wire into the existing block.
Off that I have my voltage display/clock, some under-tank lights (controlled via a separate switch), power for my GPS and a 5V USB socket for phone chargers etc (not all connected atm)
The purpose of the relay is to remove the load from the switch contacts. Not really likely to be an issue, but it lessens the risk of things burning out. Also, I can easily add in a "voltage switch" circuit or other stuff (this is a circuit that would switch the extras off at IIRC 11.5V and back on at 13V - so if I was sitting at traffic lights my extra lights, heating, gadgets etc wouldn't drain things down on me (guess where I got the idea from...
2nd pic shows the wire coming from the bottom from the battery (if the bike was intact atm) to the fuse, to the relay, and then to the terminal block. It also shows that while I am waiting for the rest of the engine stuff I better get out, get some rolls of wire, and tidy up the wiring! The other two relay wires are 1 to earth and 1 to a wire from the ignition switch as mentioned above (service manual and multimeter help you find the right wire - and do yourself a favour and do a good job of your connector, otherwise you might find your bike shuts down in the middle of a passing move!
(Actually just remembered the relay is now via a manual switch as well, after my automatic circuit died (it was installed around 2006) - haven't had the bike running for over a year (soon baby, soon; we'll travel the roads again soon, I promise!) so had forgotten I'd modified that till I could get a replacement)
I also have a "lighter socket" that can of course take other phone chargers, air compressors etc. That's off a separate line from the battery with it's own fuse. And of course a charging socket should I actually have a need to plug one in.
Still reading? Well.. For one other thing to think of. I used to have a relay across the oil light, so that if the oil light was switched ON (engine stopped) then this relay would cut power to the second relay cutting power to the electronics. A simple system with the idea that when I turned the bike on before starting, or if I walked away from the bike while it was warming up and it stopped, then the extras wouldn't kill the battery. It had a couple of design flaws however, 1) cranking for starting provided plenty enough oil pressure (turning on the extras while you still wanted them off) and 2) at idle the bike generates little more than enough power to run itself, at lights that can take 5 minutes or more to change could drain enough from the battery to kill your bike's ignition system - and at that level of drain you won't restart!
(happened to me at lights on an uphill slope, before I had the display and automatic circuit - NOT fun!)
The box for the clock was just a sheet of metal cut and folded to shape, welded in the corners (the welding giving a place to tap threads for the screws) and a sheet of perspex (that needs replacing now) fitted over top, with some liquid gasket to seal it down. Oh, and a couple of strips that fit under the handlebar clamps to hold it in place (small mod to the clamps so they'd still hold the bars)
Sorry, been a bit rambling this post - number of interruptions to my train of thought. Hope it helps inspire someone anyway.