1. To fingerspell in American sign language, the first thing to know is that always use your dominant hand. Using your dominant hand to fingerspell will get rid of any form of confusion.
2. Maintain a comfortable position as you raise your dominant hand a little bit directly in front of your shoulder.
3. The only thing you should always aim at is articulation, and also strive to maintain smooth rhythm. Having this in mind will help you to form the right letter. Also, you should not focus more on your speed.
4. Always try to maintain a definite position as you move your hand, and always give a brief pause for every letter you are fingerspelling.
5. While it is not so ideal to mouth each letter, however, you can mouth each word.
6. Slightly open your hand between the letters to indicate that a word contains double letters.