What makes a good column? I feel I should warn you before we set out that if I actually had a foolproof, definitive answer to this question, I would not be writing this article. I would be kicking back with a margarita, served by a lightly-bronzed Jon Hamm lookalike somewhere deep in the Cayman Islands, while my minions bottled, sold and collected the vast streams of profits generated by the international sale of my precious, precious secret.

Nevertheless, there are certain suggestions I can offer, painstakingly gleaned from the six years I have spent as a columnist on the Guardian newspaper, though I again must undermine myself by saying that although I try and adhere to them at all times, I frequently fail and frequently dismally so.

There is a lot to take into account before you even sit down to write any piece. If you have a brief, you need to make sure you have read it properly and understood it. I have lost count of the number of times I have noted the general subject of the piece, gone off on my own trajectory and only halfway through realised that I am heading in an entirely different direction from the one commissioned by my editor. At such times, those margaritas seem a very distant dream indeed.

With a column, however, you are generally freer to choose your subject. But, as Spider Man tells us, with great power comes great responsibility. Which is another way of saying – things are a lot easier when you are just told what to write. I write a lighthearted column in the back of the Guardian’s Weekend magazine. This means that, even if my pig-ignorance on such subjects hadn’t already precluded it, I should probably not choose to write about the latest developments in Iraq or Afghanistan.

I need to find a news story – because my editor prefers me to try and write about vaguely topical matters because the columnist at the front of the magazine usually deals with his domestic life - that is substantial enough to sustain 630 words of commentary, trivial enough that a humorous treatment won’t be offensive and interesting enough to ensure that I won’t be buried next week under an avalanche of letters from readers wondering why on earth I thought they would be willing to read a page of jokes about Anglo-Saxon diphthongs and calling for my immediate resignation.

In short, before you begin writing, you have to know your audience, know your remit and above all – know your word count. This is slightly less vital if you are writing for an online publication but if it is to go in print, you must take it as gospel. 630 words may seem like a strange number – why not round up to 650, or down to 600? – but it is what the page takes. Enjov, as my exasperatingly teenage cousins say. Though at least you could be sure they would stay within their wordage limits.

That’s the practical side of writing a good column. After that, I’m afraid, it all becomes a bit more – well, a lot more – well, almost entirely - hit and miss.

Sometimes, just sometimes, columns are easy. An idea or story captures your imagination, an arresting opening line presents itself, and the piece flows from your fingers as they skip joyfully and unstoppably across the keyboard. It makes perfect sense, it has the right pace and rhythm, it’s funny, it hits a nerve and everyone writes in to say they laughed and/or agreed with you. This happens about once every five years. For the remaining 209 weeks, you must fake it. You must fake it like a ballerina fakes smiling, up on her bleeding, battered toes, by writing and re-writing, striking out dud phrases and bringing it new ones that turn out to be even worse and abandoning them without a backward glance too. It’s awful.

That is why, to write a good column one of the most vital skills you have to acquire is the ability to turn off that second voice in your head that tells you that whatever you are doing is always going to be crap. All writers (with a few, essentially sociopathic, exceptions) and all women (ditto) have this voice. Women writers, therefore, have a double dose and can easily be crippled by it. Things are even harder these days, because the internet now allows everyone to comment on your work. The inner voice gets backed up by a hundred outer ones and until your skin thickens (I’m still waiting) you will want to kill yourself every time.

You have to learn to ignore other people’s comments (I’m operating on the ‘do as I say, not as I do’ principle here, as the husband who comes in to find me ashen-faced and weeping at the comment threads every Saturday and takes the laptop away from me will tell you) turn the inner critic off and just listen to yourself. Accept that you won’t get it right first time – no-one does. Read your favourite columnists to remind yourself that it can and will be done. Remember your brief, remember your audience, remember your word count, decide on your argument or forge your jokes and go for it. All you have to do, as the American journalist Gene Fowler once said, is sit down and stare at a blank sheet of paper until drops of blood form on your forehead. Enjoy! One day we'll all be drinking margaritas by the sea.

Read a collection of Lucy's columns in her book: My Family and Other Disasters, £7.99.

Photos: Thinkstock

Lucy Mangan: How to be a columnist