Every morning and evening the streets of Bogotá, Bratislava, Beijing and a thousand other cities are thronged with people rushing to their English lessons. The demand for instruction or just conversation practice with people who speak English as their mother tongue is enormous, and will continue to increase for the foreseeable future. The most recent impetus to learn English has come from the explosion in use of the internet, as the vast majority of its sites employ the English language. Even in countries where English has been kept at a distance (such as Italy), people are flocking to English classes so that they won't be left behind.

However the time for assuming that a charming manner and a neat haircut are enough to land you a job is over in all but a handful of places, such as Bangkok and Mexico City. Standards are creeping up, partly because of a dramatic increase in the number of people gaining a qualification in TEFL (Teaching English as a Foreign Language). The number of both public and private institutes in the UK, North America, Australia and New Zealand turning out certified TEFL teachers has greatly increased in the past five to seven years, creating a glut of teachers, especially in the major cities of Europe.

Having sounded that warning note, there are still areas of the world, from Ecuador to Slovenia, Lithuania to Vietnam, where the boom in English language learning seems to know no bounds. In cowboy schools and back-street agencies, being a native speaker and adopting a professional manner are sometimes sufficient qualifications to get a job. But for more stable teaching jobs in recognised language schools, you will have to sign a contract (minimum three months, usually nine) and have some kind of qualification, which ranges from a university degree to a certificate in education with a specialisation in ELT (English Language Teaching is now the preferred label).

TEFL training

The only way to outdo the competition and make the job hunt (not to mention the job itself) easier is to do a TEFL training course. If interested, contact the British Council (Bridgewater House, 58 Whitworth St, Manchester M1 6BB, tel 0161 957 7755, www.britishcouncil.org) for its TEFL information pack.

The two standard recognised qualifications that will improve your range of job options by an order of magnitude are the Cambridge/RSA certificate in English Language Teaching to Adults (CELTA) and the certificate in TESOL (Teaching English to Speakers of Other Languages) offered by Trinity College in London. A list of centres, both in the UK and abroad, is available from these two accrediting bodies: the University of Cambridge Local Examinations Syndicate (UCLES TEFL Unit, 1 Hills Road, Cambridge CB1 2EU, tel 01223 553997, www.edunet.com/ciltsrsa) and Trinity College London (89 Albert Embankment, London SE1 7TP, tel 020 7820 6100, www.trinitycollege.co.uk).

Certificate courses involve at least 100 hours of rigorous training with a practical emphasis. They are offered full time for four weeks or part time over several months, and the cost averages at between £800 and £900. Although there are no fixed prerequisites, apart from a suitable level of language awareness, not everyone who applies is accepted.

Short introductory courses in TEFL are also available, and these vary enormously in quality and price. Although they are mainly intended to act as preparatory programmes for more serious courses, many people who have completed a brief training course go on to teach. Many (but not all) training centres have good contacts with language schools worldwide and can assist with the job hunt.

Finding a job

Teaching jobs are either fixed up from home or sought out on location. Obviously it is less nerve-racking to have everything sorted out before departure, but this option is usually available only to the highly qualified or to paying volunteers. It also has the disadvantage that you don't know what you're letting yourself in for. One of the possible advantages of fixing up a job well in advance is that you then have a chance of obtaining the appropriate work permit.

English teaching is one area of employment in which governments are relatively generous, since locals are not being deprived of jobs. Yet few nations will process visas unless applications are lodged outside the country. Employers of TEFL teachers in many countries (for example Korea, Taiwan, Hungary, Turkey and Morocco) can usually sort out visas or at least set the wheels in motion before their employees' arrival.

To fix up a job in advance, make use of the internet - increasingly the preferred recruitment tool - and check adverts in the education section of the Guardian every Tuesday and in the weekly Times Educational Supplement, which is published on Fridays. The best time of year is between Easter and July. In a few cases, a carefully crafted CV and an enthusiastic personality are as important as ELT training and experience. Well- qualified ELT teachers will already be aware of possibilities at the prestigious end of the market, for example with major ELT providers such as the British Council and International House.

The major language school chains hire substantial numbers of teachers, many of whom will have graduated from in-house training courses. Commercial recruitment agencies maintain a database of teachers'CVs that they then try to match with suitable vacancies in their client schools. In order to be registered with such an agency it is normally essential to have at least the certificate plus some experience. ELT opportunities are available through voluntary organisations such as VSO and educational charities. There is also increasing scope for untrained but eager volunteers who are willing to pay an agency to place them in a language teaching situation abroad.

The alternative to pre-arranging a job is to present yourself in person to language school directors. Jobs in any field are difficult to get without an interview, and English teaching is no different. Language institutes cannot, under normal operating circumstances, hire someone sight unseen merely on the basis of a CV and photo. Moreover, when the need for a teacher arises, that vacancy must usually be filled immediately. Therefore it is often more effective to base yourself in your preferred destination, introduce yourself to the directors of language schools and relevant companies and be prepared to wait for a vacancy to arise.

It is still possible for people who are well spoken and well dressed and have a confident manner to charm their way into a classroom. A university degree often cuts more ice than a TEFL qualification, particularly in the Far East, where a degree is a prerequisite to getting a visa. If you are job hunting in a capital city, the British Council may be able to provide a list of language schools or advise (informally) on the availability of teaching jobs: much depends on the goodwill of the staff. To gather together a list of addresses where you can ask for work, consult the Yellow Pages, read the adverts in the English-language papers, visit centres where foreigners study the local-language or English-language bookshops to check the noticeboards and ask the staff for leads. Business schools and vocational training institutes often need teachers of commercial English.

Several factors will affect the length of time it will take to find an opening. Timing can be crucial; aim to conduct your job hunt in the month before term begins (usually late August/September or around Christmas; summers are usually hopeless). Of course, a knowledge of the vernacular language is an advantage (especially in the Spanish-speaking world), as is the ability to look convincing while carrying a briefcase. If you have no luck in the major cities, consider trying provincial cities less frequented by foreigners (Plzen rather than Prague, Eskisehir not Istanbul, Chongqing rather than Beijing).

An alternative to working for a language school is to set yourself up as a freelance private tutor. While undercutting the fees charged by the commercial institutes, you can still earn more than you would as a contract teacher. Normally you will have to be fairly well established in a place before you can attempt to support yourself by private teaching, preferably with some decent premises in which to give lessons (either private or group) and with an aggressive self-marketing strategy. You should bear in mind the disadvantages of working for yourself, such as frequent last-minute cancellations by clients, unpaid travelling time (if you teach in clients' homes or offices), no social security and an absence of professional support and teaching materials.

If you are less interested in making money than in integrating with a culture, exchanging English conversation for board and lodging may be an appealing possibility, which usually relies on having contacts or good luck.

The job itself

Native speaker teachers are nearly always employed to stimulate conversation rather than to teach grammar. Yet a basic knowledge of English grammar is a great asset, especially when more advanced pupils ask awkward questions.

At least some of the thousands of young people who blithely set off to market their tongue abroad should pause to picture in detail the range of likely scenarios they may encounter. The classroom might be an alcove in a Chinese teacher training college where there are no desks and insufficient light but 25 eager learners. It might be a 'conversation lounge' in a Japanese city, which has an atmosphere more akin to a dating agency than a classroom. You could be faced with a room full of exuberant Taiwanese seven-year-olds who expect you to sing songs and draw pictures rather than talk about verb tenses. Or you might find yourself standing in front of a class of bored and disaffected Greek teenagers, forced by their ambitious parents to attend lessons after school to improve their chances of passing crucial exams for university entrance. Your 'class' may consist of a lone Peruvian businessman who, despite knowing very little English, expects to be able to swing a big deal with an American company after a few lessons from you. How far does your 'native speakerhood' get you in these circumstances? Even a minimum of training and/or experience in teaching English is a tremendous advantage.

The wages paid to English teachers are usually reasonable, and in developing countries are quite often well in excess of the average local wage. In return you will be asked to teach some fairly unsociable hours, since most private English classes take place after working hours, and so schedules split between early morning and evening are commonplace.

Teaching of any kind is a demanding job and those who are doing it merely as a means of supporting their travelling habit may find it a disillusioning experience. At the same time, it offers opportunities for creativity, learning about other cultures and attitudes, making friends and, of course, travelling.