How do we install a CPU cooler? Anything we should pay attention to?

Different maker offers different way. What's important when installing is to attach the heatsink bottom to the CPU surface as tightly as possible without hurting CPU, and make sure the cooler won't fall off when you shake the mainboard. Generally one major point is: do not be too happy is a cooler is easy to install and very easy to dismantle. A good one is easy to install but requires a bit technique to dismantle.