One of the things that seems to drive me crazist is writing dialogue. It always sounds too stilted or too informal and slangy to be quite believable, never quite meeting in that happy center. While I suspect that dialogue will be my bane for many years to come, here are a couple of thoughts I had recently on writing (and editing) it.
On writing, the main thing I think (and I am certainly not the first person to say it) is to turn off your internal editor. Yes, most of it is not going to come out right the first time, or even the second or third. That is what editing is for, but editing can only happen if you actually get the words down on paper first.
Even if the phrases sound good by themselves, I also constantly worry about maintaining a consistent voice for each character. This problem is compounded further if, like in one of my WIPs, you have several main characters, all with similar backgrounds (they all grew up in the same small, isolated community) and who are all likely to be talking similarly to each other anyway. At that point, after panicking a bit, I decided there were two things that might be able to save me.
First, find an existing character who sounds like your character. For me, this does not mean someone in a book, but on TV or in a movie. I have to be able to hear the character's voice to know what he or she is going to say. I have to know his or her personality. I would never expect Patrick Stewart to utter the line, "I pity the fool!" any more than I could see Mr. T saying, "Cry 'Havoc!' and let slip the dogs of war." Once I know what a character sounds like, and for me that requires finding a real life model, then I can better hear when the lines I try to feed him are wrong.
The second technique is part of the editing process. I pulled out every single line of dialogue from my WIP and put them all into a spreadsheet with page numbers and character names. Now I can put every single line spoken by a character next to each other and compare them easily without having to flip through 240+ pages of text. It has helped me considerably in adding unique quirks to each character, both in terms of what they would and would not say.
So, while I still dread writing dialogue most days, at least I might have a small handle on making it work. But if anyone else has some ideas on how to make it easier, I would love to hear them!