Personal preferance, but I like Plastic Padding rather than anything else.

My old man used it exclusivly in his bodyshop even though it was dear, best stuff he recons.

Always remove the paint from the fillered areas or you'll get a 'shadow' in the paint.

Filler should be used to finish the surface, not build it up.

Put several thin skims on, rather than one thick one.

Once filled, we used to brush paint primer onto the filled areas to get a high build, then wet flat it off, found it filled any scratches well. Then primed over the top again with the spray.