Situations That Call for Fingerspelling
When you don't know a sign for a word, try to describe it by acting it out, pointing, miming, or drawing it. Don't use fingerspelling as your first choice when you don't know a sign. Fingerspelling is not a substitute for signing; it is used for words when a sign does not exist. In ASL, fingerspelling is only used approximately 10 percent of the time and should only be used for:
Names of towns, cities, and states
Specific brand names of products or services
Titles of books and movies
As a word of caution, you should know that new ASL students easily confuse the letters “D” and “F.” Use these hints: flag for the letter “F” (think of the last three fingers as a mini flag); and dump for the letter “D” (dump all your fingers on the thumb except for the index finger).