Just make sure you don't add too much paste; you don't want it squirting out the sides onto the socket and surrounding PCB.
You don’t need to apply much thermal paste – a pea-sized amount (about 3 mm) applied to the center of the CPU is recommended for AMD's most recent chips. And a pattern of five smaller dollops is recommended for recent Intel CPUs, which are longer and have their heat-generating components less centrally placed under the heat spreader. Serious overclockers and veteran builders may have their own techniques. Just make sure you don't add too much paste; you don't want it squirting out the sides onto the socket and surrounding PCB.