This video shows how to properly clean and prep a processor before a heatsink is applied to it.
Steps:
1) Get materials, 70% alcohol, Goo Gone, coffee filters, cpu package.
2)Place the cpu on a safe, anti-static surface, preferably the pad the cpu came in.
3)Tear off a piece of filter and dip it lightly in the alcohol. Clean off the top of the cpu, repeat.
4)Get a little Goo Gone on a piece of filter and clean off used thermal paste on cpu, repeat as necessary.
5)Repeat step #3.
To clean a heatsink, just follow all steps (if you can, take the fan off the heatsink)