Floor insulation install method

[Notes]

I'm putting down some heat/sound deadening stuff on the floor of my '72 C10. I know there are several different kinds, but this will be the foil on top & the sticky stuff on the bottom. Just wondering what the best method for layout is. Where to start? Side to side? Front to back? I did this in a car once & remember having to slice & dice a lot, then cut odd shapes to fill in the gaps. Any suggestions? Thanks