Don't address the editor by name
After all, there may be many editorial staff at the publication just waiting to jump at the chance to read your work and you don't want them to miss out do you?

Don't use double spacing
You never see articles or stories published in double space do you? So why should you bother double spacing your work, when someone is just going to have to convert it to single spacing later?

Don't bother checking your spelling or grammar
That's the editor's job isn't it?

Don't send return postage
Why should you assume they'll return your work? That's defeatism. If they want to publish it, they can write you a letter - surely they can afford that? And as you've paid to send it to them, surely they can pay to return it?

Don't put your name on the manuscript
They're bound to keep your manuscript and the cover letter together aren't they? No one would ever file correspondence and submissions in different places. Neither would they keep your letter and send your submission to someone else to appraise it. That never happens.

Don't tell them how many words it is
Surely they can count.

Don't use a standard font
Everybody else does, and you want your manuscript to stand out from the crowd.

Don't use a new ribbon or cartridge
Why waste ink when the manuscript will get re-typed before publication anyway?

Don't tell them you've sent it to other editors
What they don't know can't hurt them. And you can always play one editor off against an other when they both offer you publication. Surely they'll understand that they can't expect an exclusive look at your work without a guarantee to publish it.

Don't read the publication's guidelines
Your work is so good that they'll have to publish it, even if it doesn't fit what they say they want. They just don't realize they want it yet, that's all.

Just follow the tips above and you're guaranteed to remain a happy amateur for ever.