Ideally, if the die is smooth (and it should be) and the HSF surface is smooth (and it should be) you want the thinnest glaze possible. You don't want a thick coating.
Imagine pushing the cpu and HSF together without any thermal interface material at all - just bare air.
If you can visualize it, you'll imagine a smooth flat plane of metal meeting another smooth flat plane of metal - but it really doesn't work like that. There are tiny cracks and bumps and irregularites that will be filled with air, which conducts heat rather poorly.
AS3, or any other TIM for that matter, is meant only to replace that air - NOT to interfere with direct metal<->metal contact. Therefore, you want the thinnest application possible.
Personally, I rub down both the die and HSF with isopropyl soaked qtips until new qtips come away clean. Then I use a piece of plastic (like rigid cellophane) to gently spread a tiny minute amount of as3 into both the cpu core (use alternating circles to apply it) and the HSF. Then I use a clean piece of plastic to smooth the application out and thin out the layers. I end up with translucent glazes that are 'ground into' the cracks and crevices, yet are totally see-through.
Doing it this way, I greatly reduced my temps over both the finger method and AS3's official 'spackle-swipe' method.
there is no magical way of applying paste. Whoever told you they got a 5c drop after applying paste in a certain way are either laying out of their asses, or else they didnt do it right the first time.
I dont use any plastic bag, or credit card. I dont try to get the paste micron-perfectly flat either since the heatsink will flatten it out when its fixed on there. just get a thin layer that is somewhat and apply the 'sink. I use the edge of the as3 tube lol workes for me
I usually put a dab on a little smaller than my thumb nail, and about as thick as the nail and then smear it around with the actual heatsink. You don't want to put too much but you want to put enough on so that it covers the heatsink. You may even find yourself using less than what I recomended.