72 Nova floor pans! 1st time

[70Chevelle454ss]

I am ready to start the install of my floor pans on my 72 Nova. I have industrial metal fabrication experience but have never done anything on a car. I want the cleanest look possible so the pans will be butt welded in and seam sealed when done. I have the full length pans for each side. I will be doing one side at a time. I have been to to put jack stands under the car but have been told different places to put jack stands. What is the correct position? Any other tips would be greatly appreciated.

Thanks