how do i add relays properly?

[Gruelius]

hi all

gotta add a relay to run the LC-1 as my car didnt come with o2 from factory so whats the proper way to do it? i.e. what one would consider a quality job.

Should i pull battery power and the ignition signal from the fuse box? or should i just run seperate power wire and grab the ignition signal from one of the ignition switch wires?

Thanks