I've also found it's helpful to blow out the tube on the top of the
aerosol can with an air line before the foam sets. Be careful where it
goes, though...

I bought a brand that came with 2 different size nozzles. You get 2 goes
without having to clean. Now if someone comes out with a can with 5 nozzles
attached to the side, I'll be happy. Life is too short to clean those little
b*stards.

Christian.