dialouges and momentum are the hardest part about writing a good story.
You can spice up the dialouges by adding words that are richer in emotional character or by adding narration midway through speech ("I didn't know, - said the girl while staring at the knight with her swollen eyes, - I didn't know you were a dragon knight, my lord. I am unworthy of your presence)
Momentum is something that I can't explain. Its energy flowing. You need to learn how to flow energy in yourself, before you flow it in a book.