Guidelines for effective letter writing

Write Now! If you want to respond or have an idea, act now, while you are still motivated. Don't worry too much about the quality of writing, you can improve it later if you want your letter published. Even if not published, your letter has an impact!

One message Only! This means that when you see an article with dozens of statements you disagree with, you have to pick only the most important issue and respond to that. 
If you have several important messages, write several letters to different media or give your ideas to your friends for their letters.

Keep it Calm. Be polite and stick to the point. Don't stress your own political or religious background, but emphasize universal values such as the right to live in peace, self defense and the condemnation of all kinds of terrorist acts.

Be Short. Most editors won't read long letters and your message might get lost in a cloud of words. Formulate your message in clear sentences. Your letter should preferably be not longer than half a page of written text.

HOW TO SUCCESSFULY COMPLAIN?

When you see inaccurate, misleading or distorted material, including pictures, in a paper you can SUCCESSFULY COMPLAIN, at least in the UK, this way:
The British Press Complaints Commission allows for complaints to be made via the Internet (all you need is a link to the original article) if an article breaks the press code. The articles sent out today do require a prompt correction with due prominency as they clearly contradict the accuracy clause of the code (as below).

From the Code of Practice of the Press Complaints Commission:

i) Newspapers and periodicals must take care not to publish inaccurate, misleading or distorted material including pictures.

ii) Whenever it is recognised that a significant inaccuracy, misleading statement or distorted report has been published, it must be corrected promptly and with due prominence.

iii) An apology must be published whenever appropriate.

iv) Newspapers, whilst free to be partisan, must distinguish clearly between comment, conjecture and fact

Explanation of how to complain can be found on the website of the Press Complaints Commission