One of Cold Iron's great strengths is its believable and natural use of dialogue. Write what you might say or hear a friend say. There's no reason to pay reading fees, or book doctors, or that sort of thing, when you can get all the help you need for free. If you put that on paper, the reader will get bored in the first paragraph. You have to find the balance between the two.
Many writers find it useful to read their dialogue aloud.
Phrases that don't look like tongue-tanglers sometimes turn out to be when you try to say them. Sentences that looked natural at first glance sound like grade B movie dialogue when spoken aloud. I just kept sending short stories to editors till one of them bought one. I thought it was just some magazine wanting me to subscribe. It seemed odd, too, that they would send such a plain-looking envelope instead of a snazzy brochure of some sort.