My experience with cover letters have been very very minimal. I guess this is where personal preference comes into play. I have written a few cover letters however its hard to put an exact number I have actually submitted. I have tried to make a generic cover letter that I can post to any job however it is good to make sure that you edit it and look it over before you post it to a different job. I have at least 4 versions of my cover letter so I can make sure I have one for each industry that I am applying too.
9. My recommendation: Don't spend too much time on the cover letter. Make one generic letter that can be edited with details of the job you apply to. Most companies look at them however with the hundreds out there most don't require it for the job position when you apply on line. If you do submit one PLEASE make sure you don't submit one that is for a customer service rep when you are applying for a manager level post unless it is for a manager of a customer service store.
10. As with a resume, spelling, grammar and punctuation all count. If you are unsure about what to say, call a friend and use them as a sounding board or email the cover letter to them and ask them if they were to write this what would they change or add to the letter.
Tomorrow I may have the guest writer, however it does not look hopeful. If so, then I will write about Thank You letters/emails after an interview or just a meeting with a prospective employer and even a recruiter!