How would you wire up a tachometer?

[Forlorn]

I figured I'd need one and never installed one before, so any help would be appreciated.
Specifically, how would you wire it to your ignition coil negative wire if that's where it connects? and how does that look?

 

[franklin2]

Find the darkgreen/yellow wire going to the coil. You will splice into this wire. That will be skinning the insulation back, wrapping a new wire around it, and then solder and tape. Or cut the original wire, put your new wire and the old wire from the coil into one side of a butt connector, and then put the original old wire that goes to the TFI module into the other side of the butt connector.

 

[Blmpkn]

Iirc there are also tachs that just need a wire wrapped around one of the spark plug wires.