Go to more auditions. If you aren't getting seen on auditions, chances are you aren't booking many parts. In order to become a better actress, experience is necessary. if you believe in the project, take it no matter how much money they are offering. You never know. Your small show could end up on Broadway.
Act in a play. If you have been acting in lots of commercials and television shows recently, acting in a play can give you direction on your acting that you would never receive when acting on TV. Because of the quick schedule, television actors usually have a week at the most to prepare for the episode. Plays, on the other hand, have weeks of rehearsal before the show opens, which is a chance to work intimately with the director.
Take more acting classes. Not only can you observe your fellow students, but sometimes the critiques of your peers may be more valuable than the opinions of out-of-touch casting directors. Take notes in any classes you take and keep an extensive binder in case a lesson applies to a character you are playing in the future.
Study a different method. There are several schools of acting that are widely accepted, including Stanislavski, Strasberg and Stella Adler. Depending on your acting beliefs, one or all of the methods of study may be useful to your craft. Take notes on inspiring and informative passages. Save them in your notes.
Take a break. Sometimes a little time away from acting is the best way to become a better actress. As you take a break, take the time to observe people around you. Observe real people and see how your acting imitates real life, or see how it brings out a certain aspect of life that your audience may not have ever seen before.