Summarize this article in one sentence.
Find a clean dish sponge (not a scour pad) and a ballpoint pen with a removable tip.  A cheap, plastic pen works best, as long as you can easily pull off the plastic tip and remove the ink. A slightly see-through pen can make it easier for you to see what you are doing. Use your finger to feather and break up the fibers of the sponge.

Summary:
Gather your materials. Leave about 1/4-1/8 of an inch of the sponge sticking out of the pen.