If you follow the following link - Graduate Cover Letter- you'll be magically transported to the GRB webpage which provides helpful tips regarding how to write a successful cover letter.
To save you the effort of clicking, however, I will now sum up the key points. "Ah", I hear you say, "that's a bit of a cop out for this week's article, isn't it?" Not so, dear ones, because there is some life advice thrown in, sourced directly from the "how not to write a cover letter guide", provided by experience gained at the University of Worldliness and the School of Making a Complete Hash of Everything.
Firstly, cover letters will be a necessary part of your quest to gain work/work experience/internships. If they're not, there's your answer as to why you keep failing. "Letters are an important method of communication" you see, providing a more detailed and personal glimpse than your CV facilitates. "This is your chance to tell them what skills you have and why you want to work specifically for that company." They are not, as one friend recently confided to me, 'a chance to reiterate everything already outlined by your CV'. Of course the cover letter should back up your CV, or vice versa, but they perform unique roles in the process.
Good cover letters help distinguish an application, showing the role applied for, necessary dates and supplementary information to catch the eye. If done well employers will love you. If done badly, as another friend found out, you can receive responses questioning if you know anything at all about regional management, letters, or even the most basic principles of shopping.
Other golden rules: spelling mistakes look awful, they show a lack of attention to detail, y'know. On that note, steer clear of colloquialisms - my mate genuinely used the word mate at least twice. Also, anything you say can be given in evidence, so be specific but be able to back up anything you send.
On a final note, some surprising but enlightening statistics to reinforce everything: those applicants who included a letter with their CV were 10% more likely to receive a reply, whilst those who addressed the covering letter and envelope to the correct named person were 15% more likely to receive a letter of acknowledgement and 5% more likely to gain an interview.
