Before you send out that query letter to an editor or publisher, make sure it won't get tossed in the trash. Your goal is to get noticed, when you send out this query letter. The day you mail your letter, there will be many other authors will send one at the same time, so you need to make your letter special so it gets noticed and stands out.

You need to make your letter different in some way, it has to stand out from all the other letters that will be received that day.
Try to make your letter one page, if it is to long, reduce your font size but do not go smaller then 8pt. Type something in a document and change the font to 8 pt, if it is to small for you, it is to small for anyone else.
Use colored paper, not to bright but something a little different from all the white letters they will receive on the same day. Maybe gray or ivory, or a pale color.
Use creative packaging to send your letter, maybe a plain white box rather than an envelope. It will stand out on their desk, and get opened first.
Try using a heavier weight paper, like stationary paper or letterhead paper. The more professional you make your letter, the more seriously it will be taken.
Use Spell Check!!!!! You would be surprised how many letters received contain mistakes.
FOLLOW UP - call or send a note, calling is better but please remember to follow up!