Perhaps you are considering a career change and are thinking about becoming a teacher later in life. That is a very viable option. Pursue it.
Employment
Finding a job in a private school is like finding any other kind of job. You will do best if you have an active network of friends and associates who can vouch for you and advise you of openings as they occur. Individual schools post openings on their web sites. There are also several widely read job boards which you ought to check regularly. The Employment Center on this site offers more detailed advice and assistance concerning private school jobs.
If you are a foreign national who wishes to teach in the U.S., please understand that 99.9% of American private schools will require you to have permission to work in this country. You must have a Green Card.
One last word of advice: no matter how content you may be or how secure you may feel in your present position, keep yourself marketable. You just never know when you might have to look for a job. Once you have passed your fortieth birthday, your marketability becomes tied to your experience, certifications and skills. Keep an eye on your marketability.
Teaching Conditions
By now you are probably wondering what it is really like to teach in a private school. It varies, of course, from school to school. The curriculum in a Roman Catholic parochial school will be different from what is taught in the local country day school. But one thing is sure: you will not have to do what your public school colleagues have to do and that is teach to the test. Discipline is also pretty much a non-issue. Private school parents sign a contract with the school. That contract spells out the consequences for non-compliance with the school's policies. There are no constitutional rights for students as a result. Their rights are spelled out by the contract which they signed. That gives you and the school a huge advantage when it comes to imposing discipline.
Things like dress codes and cellphone use are clearly defined. School safety is rarely an issue because of the small size of private schools and strong sense of community which results from that small size. Everybody knows everybody. Private schools are a close-knit community.
Curricula
In the early years the methods of Maria Montessori and Rudolph Steiner are very popular. Religious schools offer their own interpretation and methods to reinforce their religious beliefs. Classical Christian schools in particular eschew the use of computers and focus on basics. Be aware that many religious schools require strict adherence to their principles and beliefs.
Prep schools focus on getting their students into college. Most schools prepare their students for the AP examinations which take place in May of the senior year. A handful of private schools follow the IB curriculum which teaches to an international standard.
In The Classroom
Most prep schools offer state of the art teaching facilities. 1-to-1 computing is widely used. Technology is generally well-integrated into teaching with web-based curricula and electronic communications a common feature of private schools teaching. The Harkness Table or similar approaches to collaborative learning are also widely-used. Grading is similar to the standard letter grade and GPA system found universally in public schools.
Issues
Private school teachers are not immune to all the many and varied issues facing society in the 21st century. Hazing used to be a major problem in private schools. It still exists wherever administrations have turned a blind eye to what they refer to as 'traditions.' The pressure for students to be successful takes its toll in a variety of ways including substance abuse and suicide. Corporal punishment is rarely found in private schools though indeed it is still legal in twenty-two states. Bullying on the other hand has morphed into a hard to detect electronic form called cyber-bullying. Cheating unfortunately is still with us. Like bullying it has gone electronic.
Keeping In Touch
Private school teachers do not belong to unions. So it is even more important for teachers to stay in touch with each other and keep their individual and collective networks alive and vital. Blogging and participation in state, regional and national conferences is extremely important in private school circles.


