Dialogue is far from tape-recorded reality, even though it sounds like tape-recorded reality. Dialogue has to maintain its focus on the conflicting needs that gave birth to it. The conversation may circle the tension, or even appear to turn its back on it, but it’s always in the air.
Keep it short to keep it ringing true. Try allowing no more than one sentence per character before the next character chimes in. Fragments of two or three words are fine. It’s when characters start delivering long speeches to each other that the energy and the real feel of dialogue dissipates.
Don’t use dialogue for exposition. Characters never tell each other things they both already know, or ask each other rhetorical questions simply in order to get information to the reader. Let the narrator handle the conveying of information; save your dialogue for verbal tug-of-war.
Dialogue is not obliged to offer every second of a conversation. Let the narrator take over to get past a stretch of dull, irrelevant, or repeated information by summarizing what was said. Examples:
–The two exchanged pleasantries.
–Sam blathered on for a while about his future plans, all of them unimaginative.
–Victoria repeated what Maud had told her.
Remember that you can include pauses: he hesitated before answering; she took several long breaths; they both sat in silence for a moment. These are all part of the rhythm of dialogue.
A note about dialogue in creative non-fiction: readers understand 1) that you cannot remember verbatim conversations from years ago and 2) that your sense of the past is subjective. As long as you are aiming for a psychological and atmospheric truth-to-life, you need not shy away from dialogue because you doubt your ability to be factually accurate.