Wipe with water or mineral spirits while still wet. If dry, scrape carefully with a thin plastic spatula. If the stain still shows, rub with rubbing alcohol.
Pen ink
:
Acetone or paint thinner.
Shoe polish
:
Acetone or paint thinner.
Tar
:
Acetone.
Others
:
Start with concentrated cleaner, then acetone.
After removing the stain, rinse the area with a damp cloth to remove residue