If you haven’t already seen this blog, postings of real cover letters sent in by job applicants, you should peruse it. Not only for the comedic value, but to understand a little better what it is recruiters go through, just a little, with all those resume and cover letters we see.
The key to avoiding finding your cover letter or resume on sites like this? Avoid slang. Offer clarity in what you seek, and what you offer, not confusing chatter. Less is more. And so on.