I'm going to sound like a total snob as I say this, but here goes....

Spell check! Get someone who's good with that kind of thing to go over it and make sure there aren't any boo boos. Your computer's spell check function is fine for spelling, but won't tell you if you've used the wrong word, etc. I'm quite good with that kind of thing and have been cocky in the past, sending something out without a thorough edit. Big mistake! Improper grammar, spelling, punctuation, etc, looks unprofessional. It's much easier to fix it before it's sent out. I spotted a few boo boos in your draft (it's a terrible habit of mine) that you definitely want to fix before firing it off to clients.