If I'm writing alone and I don't know how to resolve a scene, or improve it etc. I tend to go for an hour long walk. I start off thinking about the idea, then inevitably daydream about something else for a while, then pull myself back to the idea, then daydream...somehow the breaks of random unrelated daydreaming seems to make connections in my mind and by the time I get home I either know what I'm going to do or I've made some kind of development.
I also read aloud, but I reckon you just have to do that to hear how it flows properly. That's your fine-tuning stages, to me, where you're fiddling with individual lines and words.
Last stage for me is to send the whole finished thing to a writer I trust that tends to have the same tastes as me for some harsh-as-possible feedback.