Are Clean Hands Essential?
Just how essential are clean hands? The quick answer is VERY essential. It is well known fact the after working with clay for long periods your hands tend to pick up the colors you are working with. Reds and blacks are probably the most noticeable. Maybe you don’t see a color change with using light colors but these is still a film of clay depositing on your hands.
Many of the polymer clay artists advocate baby wipes to clean your hands. I am truly frugal (read cheap) and cannot justify purchasing something that is a one-time use item. Because of that, I wash my hands a lot. Soap does not always remove the film of clay on your hands even when you use a scrub brush.
What Is My Solution?
I sometimes use Boraxo and it works very well. But both of those cleaning methods can have a drying effect on your hands when you are washing them so often. I now use a simple DIY sugar scrub that works great for me. It removes all of the clay film and leaves my hand with a layer of oil that keeps them from drying out. The scrub also works well when I have black stuff all over my hands from metal polish. I keep a jar of it in the bathroom next to my studio.
Simple Sugar Scrub Recipe
The scrub is a simple recipe of sugar, oil and essential oil to give it a nice smell. You can find sugar scrub recipes all over the internet. 
Mine is very simple. Combine one cup of sugar with enough oil to saturate the sugar totally and add 5 to 10 drops of an essential oil scent of your choice.
That’s it. Put it in a jar and plop it down next to the sink you use most often. The essential oils I use are lemon and grapefruit because of a fresh clean smell. The choice of oil is based on what you like and what you have available. I use olive oil, but coconut or almond would also work well.