EXTREME CAUTION: Don't use solvents like Brakekleen, MEK, gas and carb cleaner.
I know a guy that washed his hands with carb cleaner on a regular basis.
He got liver cancer and is now dead! But he has nice clean hands!
That last tip of scraping a bar of soap is a good one.
There is a product I get from an automotive paint store called "Paint Buster" I think it's from 3M. works GREAT!