Hood liner?

I'm looking to quiet some of the noise coming from my engine
compartment on my '90 Celica. Though it's not overly loud, I'm looking
to make it as quiet as possible. The first option I thought of was to
install a hood liner. I have heard that this can be rather effective

Does anyone have any recommendations of a hood liner that would work? I
have seen Dynamat but from what I hear it's just far too overpriced and
features the same quality as products that can be purchased for a
cheaper price.

How difficult would it be to install the hood liner (my guess is simply
clean the hood, then place it and cut)?

And one final question: What else can I do to help quiet my engine
compartment? I am hoping to have it quiet on both the outside and
inside of the vehicle.

THANKS.