I´m currently prepping some Slotta-ed Commandos from I-don´t-know-what-manufacturer and will re-base them to washers, removing the tab, then glueing the feet to the washer after roughing them and the base up with a file or sanding paper. Then, the hole is covered over with thin paper.
Edit: Whoops, forgot to add on the white issue.
I also choose the method depending on what kind of effect I wish to create, but usually I start out with a good, clean white layer added to the basecoat, then washed to create effects:
- light sand for ceramic:

The rough finish is due to the casting, which I only noticed after varnishing. Duh!
- various shades of blueish gray for cloth, middle figure:

- white lined with black for plastic look, with a satin varnish sheen:
