i used a fairly strong mix of washing up liquid and water myself, thinking that it would help lubricate it better. Also soaked the paper in for a good few hours before.
the higher the grade you use the easier it is to polish out the marks, and the less paint you'll be removing. I started with 2000 to see what would come out easily then had to go down to 1000, then 1500,2000,3000.
i used the least abrasive polish i have until it was only the deeper marks remaining. Then i went up a polish at a time until it was at a decent level. (polished out by hand)
Also pb's pro polish2 gets sanding marks out very well.
