The life of professional ballet dancers, especially if he or she is just starting out as a professional, can be very unpredictable and low in pay. Professional dancers work on a contract. A dancer will go and do a class with a ballet company and tell the company that he or she is interested in getting a job with them. The class is treated as an audition and afterwards the directors of the ballet company will tell the dancer if they would like to give him or her a job. If they do, they will offer the dancer a contract. The contract will be for a certain number of weeks at a certain pay rate and will include all of the benefits that the company will offer the dancer. For example, a young male dancer just got a job with a company and his contract is for at least thirty weeks, (he may work for more), and the ballet company will handle all of the immigration arrangements and other arrangements because he is from out of the country. This is considered a pretty good contract.
As a dancer gets better he or she may be promoted to the position of "soloist" within a company. This means getting to dance solo roles, (such as the bluebird in The Sleeping Beauty), and get paid more. Then, a dancer may get promoted again to become a "principal" dancer with the ballet company. This means another pay raise and the opportunity to play leading roles such as Don Quixote in Don Quixote.
If a dancer is good enough and well enough known he or she may do some work as a guest artist with other dance companies as well as work at a particular company. This is a way of raising the dancer's image and supplementing present income so that he or she may live comfortably.