First clean processer and heatsink with something like alcohol. Depending on the processor, squirt a small amount (half a grain of rice for p4, grain and a half for amd64 if I remember correctly). Then just bolt down the heatsink or whatever nice and tight. Spreading it out is bad, just gets dust and such in there. Also, they recommend just twisting the heatsink by a few degrees when its on to remove air bubbles etc.