This short bit of writing might better be called "Different Types of English Teaching Careers in Thailand"! This is because not everyone wants to be "confined", as it were, to working for just one school. Many teachers prefer to set up an ideal work schedule (for example, 9-12 AM M-F, 5-7 PM M-F and 9-12 on Saturdays), and then locate schools where their talents are needed during those days and hours. Private students can help fill in the desired hours, and teaching them can be quite remunerative, provided that there is a strict class-cancellation policy which favors the teacher, and that the students to be tutored are reasonably well off financially. (There are plenty of those in Bangkok!)
However, for persons just starting out as EFL teachers, it may be better to seek out just one school, or not more than two schools, which really needs them, learn how things are done there and then perform well and reliably until they really feel comfortable in all teaching situations. Many teachers do not wish thereafter to teach in any other way. For the benefit of those teachers, the following information will be useful.
Universities. Universities will require at least a bachelor's degree, and many a master's degree, in addition to your TEFL course qualification. The pay, including benefits such as housing, can range from about 40,000 baht a month to about 60,000 baht a month, and sometimes more. As there are no evening teaching hours, typically, teachers are free to tutor private students in the evenings, or work in companies or language schools (without informing the university)! Some universities do offer English teaching opportunities in the evening, and these are rather well paid.
International schools. These require at least a bachelor's degree and a TEFL qualification. Salaries can range from about 45,000 baht up to 70,000 baht or more per month, generally without a housing allowance, the actual salary amount dependent upon which school you work for, and how many subjects other than English you may be able to teach. Certainly a state teaching qualification from your home country will be a plus for you in seeking work with international schools, though many teachers there do not have them.
Bilingual and government schools. Bilingual schools may or may not be government schools; thus it is possible, given other requisite qualifications (such as a TEFL certificate), to teach without a degree, but you must be really good! Government schools require a degree, period. In any case, you may be assured that TEFL-trained teachers are urgently needed by all of these schools!
Private schools. If you can teach well, have a TEFL certification and love and have patience with children, you can certainly teach for private schools, though if you have any other type of certificate at all (carpentry, for example!), it does help you soometimes to get past your interview. Teaching full-time for a private school (typically about five 50-minute periods a day from 08.30-03.30 hours M-F) will generate a monthly income ranging from 35,000-45,000 baht in Bangkok, somewhat less in the provinces. In fact, many of our teacher trainee graduates get work in private schools almost immediately after finishing our course, simply because we normally have contracts with up to 30 or 40 different schools ourselves. An advantage of teaching in a private school is that you will have free time every evening and throughout the weekend - though part of that "free" period will certainly be spent in checking homework and constructing and grading exams. New semesters start, normally, around the middle of May to the first of June, and around mid-September to early October. You may get work at other times, however, if one of the existing teachers leaves, of if a new course suddenly opens. You may also be invited to teach "summer school" for about 20 days during April.
Language schools. Most Thais with a genuine need and interest in improving their English skills, either to fulfill their personal goals or to benefit their companies (or find work in one), study in language schools. Thus, language schools satisfy a very important need in a lot of Thai people's lives. A TEFL certificate, along with a successful teaching demonstration, is normally all that is needed to land a job in a good language school, though some experience is regarded as a "plus". In this setting, you may be engaged to teach only on the school premises, or on the school premises during day hours and then at company locations in the evenings, to teach the staff there. Salaried positions in language schools these days range from 35,000-45,000 baht per month in the case of successful institutes with few locations, down to 25,000-30,000 baht per month in less discriminating schools (especially with multiple locations), to even less than that in what one might justifiably call the "garbage schools", who have little concern or interest in either the students' welfare of the teachers'. In any case, we will give you reliable guidance about the best language schools to work for, in the event that you will not be working for our own. Lots of part-time work generally is also available at language schools, and this is paid on an hourly-rate basis. Beginning your teaching career in language schools (perhaps splitting your available teaching hours among 2-3 of them) is often an excellent way to start out, as you will likely be asked to teach classes of all types and levels, gaining for you solid, multiple skills which will be useful to you everywhere else later on.
Companies.Qualified teachers often approach companies directly and receive higher-pay offers than they would if they were working for a language school. However, when courses finish up (and do not renew), teachers may find themselves "out of work" for a considerable period of time, while they are seeking out new companies to engage them. Having said that, there are companies who have been using the services of the same teachers for years, without significant interruption! Finally, if you get your company job through a language school, and do well there, you are likely to be offered more company work as soon, or almost as soon, as you have finished your teaching for that company. Some teachers actually make a career of this, though, generally, other teaching situations and teaching hours will need to be found in order to "pad out" a teacher's income to reach the targeted amount.
Private families. If you have Thai friends who know you have received a teaching qualification (and, if you are friendly, you certainly will!) - You will never, ever be out of work! Just be careful, as we have cautioned above, to make sure you have a strict class-cancellation agreement with your students, or you may spend 6 months completing a one-month course! It's also a good idea, if you plan to teach families extensively, to teach for a large number of families who have enough income to afford your reasonable high demands! Indeed, you may also wish to teach other families for less income because of their need and interest, and largely because you have become a caring and loving teacher yourself, and simply "can't refuse"!
In summary, the demand for you as a trained teacher far exceeds the supply of trained teachers. If you are a "people person", you will never be without a comfortable level of income in The Land of Smiles!