​In recent years a story appeared in the New York Times about a woman who had spent decades in therapy and didn't think it had worked. It provoked heated debate. Had she been used badly by an exploitative profession, or was she herself at fault for persevering in a therapy that she could plainly see was ineffective?

Unfortunately, questions like these don't have easy answers. However, they do indicate the need for people to think wisely about their choice and usage of therapy.

The good news about therapy is that mostly it works. Whatever kind of therapy you do, you are likely to find relief from distress and gain psychological benefits.

On the other hand, things can and do go wrong. A widespread and insidious problem in my experience is the one described above: an ineffective therapy, or one that makes the client feel worse.

How to steer clear of this?

It is all too easy at moments of psychological distress to make hasty and ill-judged choices. Yet it is critical to be a discerning therapy shopper and consumer - after all, this is a purchase that could affect your whole life.

Here are my top tips.

1. Get support while you are looking for therapy

If you're in distress, ensure you have some form of immediate support to tide you over while you investigate other possibilities. Make regular contact with close friends - the ones you can really talk to; talk to the Samaritans they don't just deal with the suicidal ; go to a self-help group in your area.

It is essential to ensure that your life is rich with activities known to enhance wellbeing: exercise, doing things to 'detach' from everyday worries meditation, creative activity, the arts , connecting with other people, doing things that give you a sense of deeper meaning or purpose in life, learning and experimenting, and - surprising as it may seem - helping other people.

Even when you find a therapist, don't have all your emotional eggs in one basket. If you feel reliant on a therapist to tide you through from week to week, you will find it harder to be objective about therapy's usefulness to you. Worse, therapy may become a 'crutch' supporting a dysfunctional life, rather than a route to change.

2. Get informed and clear about what you want

There are at least 400 different kinds of therapy based on very different ideas. Many of these are effectively different 'brand names' for a broadly similar process. However, there are some radical differences between therapies in terms of what problems they are known to address; their underlying belief systems; the nature of the process, and the cost and time commitment involved.

Think carefully about your own personal 'therapy spec', talk to potential therapists about what you want, and ask them whether their approach fits with your own needs and wishes. Here are some of the factors to consider.

• Do you want relief from specific symptoms which ones? or to get support through a crisis? Do you want to change a behaviour, or to understand yourself and the meaning of your life better? Are you looking for support to make a big life-change?