Artic silver, and changing heatsink question

[Caanon]

Right now I have a p4 2.53 with Artic silver 3 and retail HS.

I have an alpha HS on the way in mail.

What is the best way to change to alpha+AS3

1) clean the cpu with some type of cleaner, reapply
2) wipe off most of the As3, dont worry if miss some, reapply
3) Don't worry about cleaning it, just take off retail HS, and reapply if some more might be needed, and put alpha on
4) other????

Thanks