By having "good ears," you can capture all audible English speech and important sounds that are relevant to a video's storytelling. Paying close attention and listening to all the audio will help ensure that the resulting captions are complete and accurate.
Google can be a captioner's best friend. You may find yourself captioning an audio file that contains unfamiliar words, proper nouns, or phrases that you are not familiar with. A quick internet search can make sure that you are using the correct words and terminology.
Attention to Detail
Every great captioner knows the importance of proofreading. By reviewing your work before you submit your captions, you can check to make sure that the captions are accurate and read clearly, include correct placement of captions to avoid covering text in the lower third, and accurate syncing to within a 1/2 second to the start of the audio.