Frankfinn Institute of Air Hostess Training.

Institutes like Frankfinn give you a basic outline of how to appear for any job interview and how to gain confidence in your moves and be personable.
Being presentable is also what matters a lot to be a cabin crew in any airline. Because this job is a part of hospitality.
To be a cabin crew the most important thing is to be confident, personable and clear in communication. Cabin Crew are face of the airline because they are the once who remain with the passengers for the maximum amount of time. Hence it becomes most important for them to be personable and pleasing in communication and presentation.
In domestic sectors it is helpful to be aware of regional languages of the places where the airline operates. So that they may put you on roster for those flights.
In case of international airline, the most important thing here is the same, to know the language. If you are targeting some international airline then learn some foreign languages apart from English. You may go for French, Thai, German, Chinese or Japanese.
A lot of airlines operate to destinations where such languages are spoken.
PD (Personality Development) Classes can be a good option to prepare before you walk-in for any interview.