I wanted to install a kill switch in my 89 and wanted to know how I can do this and what I need ?

 

Waste of time; any good thief can jump a starter.You only need to put a screwdriver across the terminals on starter and it bypasses any switch you have
Better to install a cut out on Ign ( coil ) or fuel.
Much harder to bypass if done correctly

 

So how can I go about doing that then?
Which ones better the fuel or coil one?

 

 

If you run a wire ( hidden in the factory harness so it looks like stock ) from coil Neg terminal to ground through a switch then if someone hot wires the coil direct from the battery ( most common way to bypass the Ign switch ) then they will get no spark.
Edit
As the white wire from coil Neg goes to tacho you could splice into that wire under the dash to achieve same result without adding any visible wiring in engine bay

Or you find the wire that goes to the elec fuel pump and put a hidden cutout switch on that.

 

Ok so I already know which wire the fuel pump is so all I have to do is connect a switch to the wire and ground it ?
Which one is the coil ?
Thanks for the help

 

No
all that will do is make a direct short to ground and blow your fuel pump fuse ( if you don't have a fuse your car may burn down )

You cut the pump wire and put a switch in ( connect both cut ends to switch ) to turn the pump off or on

 

Yea I have a fuse that's by the headlight.

So a normal toggle switch is fine ?

 

Should I install another fuse With the switch?

 

All circuits should have a fuse somewhere ( as close to supply point as possible).
If you have added extra wiring then you should have it fused

 

Do like I did and make one for each one