I like to use 3-m (super) trim adhesive spray, and also 2-tubes of yellow weather strip adhesive.

Before fitting the hood pad back on the car, I like to do a dry fit to see where the new pad will lie and get a visual in my head.
Then I spray the super trim adhesive all over the hood pad, then squeeze 2-tubed of that yellow weatherstrip adhesive(advanced auto parts), on the hood pad in a squiggly fashion all over.

I let the glue get tacky for about a minute or two, then, with the help of an assistant, place the pad on lightly and line everything up, then press the pad on and firmly push the pad with my hand in a wiping fashion to get the pad to stick in every possible spot.

It is a good idea to make sure the hood is straight up, in position 2 so the pad has a lesser chance of sagging.

Keep the hood up for at least an hour before driving off.
That should give the glue time to set up.

Also, before I attempt to scrape the old pad material off, I lay a large sheet of plastic over the engine compartment and fenders to keep the debris off the engine, and it makes clean-up very simple.