Avoid dish soap. It's a harsher detergent.

Get some glycerine and castor oil from the drug store and pick up a container of the thickest liquid hand soap you can buy. Mix the glycerine and soap 50-50 then add about a a tenth again of castor oil. This makes a nice slick lube that can be washed off easily.

Some of the guys use the silicone spray called "Son Of A Gun" but I don't like it because you can't easily wash it off or ever again tie a knot in the rubber if required.

Free Flight Forever Dude...