How would I go about installing a custom stereo system in a 1968 ford torino?

How would I go about installing a custom stereo system in a 1968 ford torino?

Added (1). I have the original stereo which I will keep, but I wanted to restomod this car and give it a newer stereo system. I don't think the original radio works (I can't get it to work, haven't extensively tried to get it to work though). I kind of want a bluetooth stereo system with decent speakers and a decent size (~10-12") sub probably underneath the back seat?

Any tips or advice would be appreciated.

Should I have a fuse? Would the fuse just be on one of the lines from the battery? What are al

Added (2).. All the mods/connections I need to worry about? How much would parts run me?

How much would it cost rather to have someone do it and who would you recommend?

I know it is a loaded question, so much appreciation!

Knowing nothing about stereo installation as I do, I would hire a professional.