Keywords are useful. Fill out the title, description, and tags so that your video appears in searches.
Consider different ways to search. "Meow," "cat sound," "cat noise," "cat says," and "animal noise" could all be looking for the same thing.
Being active in a community also helps build up your profile. As people see you around, they'll get curious and investigate. Comment on other videos. Use forums. Link your Youtube account to your Facebook, Twitter, Instagram, etc.