Ensure your cover letter is short
Address your cover letter to a person—an actual person!
Specify how you found the person that you are emailing.
Be explicit as to what job you are looking for, if it is an exploratory request, or submitting to, if there is a job posting.
Do not write the cover letter as a prose version of your resume.
Help the reader connect the dots as to why they should take action
Find out more about all 6 ways and the complete Chameleon Resumes article