Dialogue for some people is the easiest thing to write. I've always found it more difficult than other aspects of writing.
One thing I constantly battle in the revision process is character voice. I notice I tend to have several characters who have a very similar voice as the work progresses.
Does anyone have character voice exercises they use to good effect?
I do extensive character sketching but sometimes this still gives me difficulty & I wind up having to do a lot of editing during a 2nd draft to overcome this.