Martians using their Earth-watching instrument must notice that this is our swarming season. During July and August prodigious numbers of two-legged creatures may be observed criss-crossing the globe from continent to continent.

Seen from afar the majority seems strangely afflicted, with a very large tumour on the back and a smaller one under the chin. As the Martian instrument is equipped with an X-ray, many notebooks show up; and its mind-reading capacity exposes thousands of ambitions to write travel articles. It also has a prophetic component which registers the sad fact that few of these ambitions will ever be realised.

Forty-four years ago it was easy. Aged 19 I got on my bike, cycled around Belgium, Germany and France, returned home and wrote articles for Hibernia - an Irish monthly journal of good repute, long deceased. That modest success paid for my next cycle tour, in Spain, which inspired a series of articles for a daily newspaper. And so I went on . . .

It was easy, then, because comparatively few were competing on the scene and many more journals - like Hibernia, the Cornhill Magazine, Blackwoods - offered opportunities to literary acolytes. Also, I had the element of novelty on my side. In the 1950s not many young women cycled alone around Europe. To arouse equal interest in the 1990s one would have to ride a unicorn across Siberia.

Should you happen to visit a travel editor in hisher office, you will notice an ominous number of typescripts stacked on every available flat surface. The snare is that after a stimulating journey, to wherever, getting travel articles published still seems as easy as it really was in my youth. You know you have a flair for putting things down on paper; everyone enjoys your letters from abroad. You know about travel writing’s popularity; every year the bookshops’ travel sections expand. What you may not know, until you have learned the hard way, is that the travel article market is shrinking, despite the boom in travel books, and is by now thoroughly saturated.

Commissions are reserved for the elite of the profession, stylists like Colin Thubron and Jan Morris whose writing is appreciated for its own sake, quite apart from the interest or location of their subject matter. In the national newspapers only a small group of freelance travel writers appear regularly; for cost-cutting reasons there is an increasing tendency to employ staff journalists rather than freelancers. Moreover, not only beginners are confronted by this obstacle. For 30 years I have been writing moderately successful travel books, my name is quite well known, yet nowadays I would find it difficult to place travel articles - especially as I am not a photographer and travel editors have become irrationally addicted to top quality illustrations.

And yet - there’s nothing to be lost by trying. (Except two postage stamps, one for the SAE). There may be something strikingly original about your experiences, impressions, reflections, interpretations. You may have an eye for those minuscule but significant details which go unremarked by the average traveller and lift your piece out of the rut, making some weary travel editor sit up and rejoice. Or you may have a command of language that gives your description of Bognor Regis a sparkle entirely missing from other people’s descriptions of Borneo or Brazil.

On balance, however, those with serious ambitions would be wise to concentrate on the book market. Although it, too, is threatened with saturation it is more accommodating than the journalistic one. While gaining in popularity the genre has extended its boundaries to include many superbly crafted and idiosyncratic books that could as accurately be classified “autobiography” or “history” or “philosophy” or “zoology”. At the other end of the scale are all those vigorously hyped volumes describing in homogenized prose some sponsored feat of endurance or a stunt journey notable only for its pointlessness. And in between are various accounts - often entertaining andor instructive - of students being scientific on behalf of their universities, doing earnest research on the movement of icebergs or the incidence of river-blindness in Mali or the building techniques of the Karoo weaver-bird.

And so, having decided to attempt a travel book, you can feel intellectually foot-loose and fancy-free - constrained only by the length of the school holidays. Not by money; if you travel beyond the First World you can live on quarter your salary and actually save by being abroad during the vacation.

Undoubtedly, for teachers, time is a major problem; one summer holiday is unlikely to yield enough material for a book. But this problem could be solved by devoting all of two summer holidays to the project. In which country? That must entirely depend on where you want to go; don’t try to calculate where might be most saleable or topical. Go where for you there is something special, pulling you there.

Wherever you go, there will almost certainly be guide-books available. Read them attentively, with map to hand, then plan a route avoiding all the places they mention. Otherwise you will find yourself surrounded by a teeming multitude of fellow-travellers whose presence will inevitably insulate you from the local people and the everyday realities of life as it is lived in non-touristified regions. Don’t waste time reading travel books about your destination - at least not until you have finished your own book. It is best to respond to a new environment, physical and social, unprejudiced by other viewpoints and experiences. However, should you be brave or rash enough to choose an area of present conflict - Angola, Bosnia, Tibet - it would help to study the politics of that conflict from every angle (not just the angle presented by the mass media) before departure. And of course history homework is essential. If you know little or nothing about a country’s past, you won’t be able to make much sense of its present.

Some travellers like to pre-plan, to know exactly “where, how and when” before leaving home. This makes sense if some specialist interest has determined your destination and will dictate your route on arrival. But if you are simply travelling for travelling’s sake it is much more relaxing to let chance events and encounters shape your journey. To design it as though you were a one- person package tour (“Must get to A by the 15th, to B by the 16th and must be in C by noon on the 19th”) is an absurd self-limitation. On the 15th you may notice a fascinating little temple high on a mountainside way off your main route and you should feel free to investigate it. Or on the 16th you may meet an interesting character who offers hospitality, gets you involved in local excitements and delightfully delays you for three or four days.

I am assuming that you have prudently decided to travel alone. Some of the finest recent travel writing has been produced by authors who did have a companion or companions and occasionally (Redmond O’Hanlon and William Dalrymple are obvious examples) travel narratives may be enriched by hilarious descriptions of inter-personal relationships. But I see these as the exceptions that prove the rule: if you want to get as close as possible to the country of your choice, travel alone. In non-European countries even two foreign travellers are perceived as a “group” by the locals. Between them, these two involuntarily create an aura of self-sufficiency; they are not completely dependent on the locals as the solo traveller so obviously is. Also, however congenial your companion may be in other circumstances, shehe is too powerful a link with your shared world back home and thus impedes not only your merging with local communities but your gathering of unique personal impressions, your individual reactions to the unexpected and the unfamiliar - your general sensitivity to “the spirit of place”.

Don’t be spatially greedy, covering too much ground in a short time. Today this is a common temptation, encouraged by the penetration of motor roads into areas accessible only on foot a mere decade ago. For the travel writer, self- propulsion is best. A few of my own long journeys have been by bicycle, the rest on foot with a pack-animal (pony or mule) to carry all my gear. Trekking has many advantages, not least its allowing you to escape for weeks on end from motor roads and all that goes with them: petrol fumes, noisy grinding gears, white bread, packaged crisps, consumerist litter, Coca Cola and the sort of people who confuse Coca Cola with civilisation. However, for teachers planning a two-part journey investment in a pack-animal is not very practical; it can take a week or two to find the right animal - unless you want to quit teaching and get in shape for joining the SAS. So I recommend that you get on your bike. This will enable you to avoid the worst of the motor roads while automatically curbing any latent tendency towards spatial greed.

Another alternative, for the less energetic, is to choose one place - a city, town or village - and settle there, renting a room, catering for yourself, establishing a network of friends and becoming familiar with regional customs, problems, entertainments, attitudes. For time-restricted teachers, this could well be the most productive ploy. In the interval between Year One and Year Two a correspondence might be kept up with those new friends (unless you choose a village of illiterates, easy to find in Third World countries) and thus your intimacy with the region would not be confined to the two holidays.

When your book is finished, what then? It is important, I’m told, to have a literary agent as protection against the shoals of publishing sharks currently infesting the literary ocean. Myself, I wouldn’t know about that; for 30 years I have had a non-predatory publisher against whom no defence is needed. But not many of the ilk of John Murray have survived into the 1990s and it may well be true that your succulent masterpiece will attract sharks. So look up “Literary Agents” in the Writers’ and Artists’ Year Book - and even after that stay on guard, lest the agent turn out to be a shark in whale’s clothing.

Good luck!

Dervla Murphy’s latest book is The Ukimwi Road (John MurrayFlamingo) about cycling from Nairobi to Zimbabwe.