I did this yesterday, and it helped. I bought "rubber foam weatherseal - self stick tape" 3/8" wide 5/16" thick 10' long and might have used half of it. It claims "minimum compression - superior shock absorbing" on the bag it's in.
The three clips on the headliner are the approx. 1 1/2" by 5/8" plastic rectangles, rotate 90 deg and they come right down. I put foam on top of the brake light housing and all around the headliner where it meets the rear window.
I also foamed the front overhead console a bit. It makes a good bit of noise, too. You have to pull it down a bit (there are clips all around it that pull out) then reach in from the top-rear and push out the blank panel (the 4x6" one) to access a single screw in the middle. Then it hangs by its wire lengths enough to put this foam tape in it. Just be careful to not put it too close to the edges - you can see some of the foam if it's too close to the edge.