Make sure you don't get the thermal paste on the pins of the CPU or in the socket. most pastes have a metal compound in them and it could short out your CPU/mobo.

And remember a CPU is a ZIF socket. that stands for Zero Insertion Force. If you have to push it in you are doing something wrong. you might have to tap it just a little to make sure it is seated but DO NOT PUSH.

I don't know your level of expertise so i am just making broad suggestions so do not be offended.