Cover Letters
These days a large percentage of jobs advertised require cover letters to accompany CVs. Even if they don't specify that a covering letter is required, it's quite a good idea to include one. I don't intend to tell you how to lay out a letter; such as your address at the top right of the page, the employer's address just below on the left hand side, etc. I'm presuming you already know how to write a letter, I'd like to just give my opinion on how you should lay out covering letters, whether they are for a speculative application or in response to a specific job advertisement.
SPECULATIVE APPLICATIONS
If you are applying to a company where a job hasn't been advertised you should start your letter stating that you are interested in a specific position within that company. Try to find out the name of the person who the letter should be addressed to rather that just "Dear Sir/Madam" if you really can't find out the name of the person the letter should reach ensure that you don't just type "Dear Sir" this is sexist to assume the manager will be a male I've received emails and covering letters addressed this way and I was not impressed. In your opening paragraph you should also show that you've researched the company and they are the sort of organisation you can really see yourself working in or something very similar. Recruiters love flattery but don't overdo it. Saying "I've heard so much about your company it's the only company that sells this fantastic product" is going over the top especially if the company is not the market leader in that area.
Once you've mentioned the sort of position you're after, provide a summary of your key strengths that are relevant to the position including how much experience you have of that skill, such as "2 years people management experience" or "18 months call centre experience" or "3 years sold office administration experience".
After this section you should state that you would relish the opportunity to gain the chance to have an interview with the recruiter or be happy to answer any queries they might have about your background/skills (as clarifying some areas could be the difference between getting an interview or not).
Finish off your covering letter advising which is the best way to get hold of you, be it a landline or mobile telephone number or email address. If you do ask them to contact you by email at least make sure you check your email regularly. Imagine how you'd feel if a recruiter dropped you an email asking to arrange an interview with some suggested dates and you didn't check your email for a week! It doesn't look very professional at all!
APPLYING FOR ADVERTISIED POSITIONS
Really all of the above should apply when applying for a job which you've seen advertised bar a few additional things to bear in mind. These are very important I'll explain why at the end.
If you advert has a person's name, address the person directly in your covering letter/email. If the contact details are listed as "Jane Jones" it's sensible to address the letter to Ms Jones rather than assume she is a Miss or a Mrs. If the contact details are listed as "L Smith", it's impossible to know whether it's a male or female, so address the covering letter/email as "FAO: L Smith" then start the letter with "Dear Sir/Madam". Some companies deliberately do this to see if you make assumptions. Don't assume things when it comes to applying for jobs, recruiters could be testing you.
It's best to state in your opening paragraph that you are applying for "job title" role and specify where you saw it advertised. This is actually helpful to recruiters so they can work our how effective their recruitment campaigns are and if you include this information without being asked you will gain brownie points. If the job advertisement asked you to include a summary of your relevant skills, make sure you do this. Recruiters hate seeing covering letters which consist of 2 lines saying they're applying for a job and would love to be interviewed! Use strong descriptive phrases such as "led a team to complete xxxxx project" or "successfully built up a customer base of xxx" or "instrumental in setting up xxxx", etc. These phrases show you are capable and literate.
If the job advertisement asks you to specify your salary requirements, don't ignore this request. Employers would not specifically ask for this information unless they needed it. By ignoring this request you're a) taking up more of the recruiter's time in that they might have to contact you to get this information, b) showing that you can't follow simple instructions and c) possibly losing your chance of even getting to interview stage as they might not even bother to contact you to ask for this specifically requested information.
The main reason it's important to follow specific instructions for applications in job advertisement is that recruiters are very busy people. For one job advertisement alone they could receive hundreds of applications. They WILL look more favourably at the ones who've supplied the requested information and often they scan cover letters to ensure the relevant info has been included.
So overall make sure your covering letter has enough relevant information to make a good first impression good enough to get you an interview and that it contains ALL of the information requested if you're sending it in response to an advertised position.
Good luck!