A good practice for me is to print out the story so far and then read it out loud. Slowly. Taking pen to obvious mistakes and changing 'stared at' to 'stares at' etc. I'm writing A&J in first person and I keep lapsing back into narrative mode. I seem to think in both modes while I'm writing ;-)
After reading the first draft a few times and giving it to a good friend to read it was pretty obvious that it needed more 'meat', more story. Bill said that he really like the story but at only 50 pages he found that he wanted more when he got to the end.
Now I think wanting more at the end of a story is a good thing. But in this case Bill said he also found that he wanted more during the story. I had some great scenes but they were too sparse, they went by too fast. There were lots of places he wanted to 'see' more action.
So. I'm in a 'where' are the thin parts of the story' mode now. Not too surprisingly I'm finding lots of places where I can improve and enhance the plot. This is good. This is so much fun it's probably not legal. ;-)
Print it out. Read it out loud, slowly. Listen to the story. Maybe have someone else read it out loud for you so you can concentrate on following the story. Try it, and let me know if it works for you.
Be in the moment, everyone. Best of luck!