Critiques groups are helpful. One of the most useful things one writer can point out is another's bad habits: overused words, gestures, and sentence structures. Recognizing one's own bad habits is difficult, typically because we don't realize how they come across to readers or we don't even realize that we're stuck in them.
After some insightful feedback, I'm working to cut filter phrases. Things like "she saw," "she heard," "he felt." These phrases distance readers from the action, so it's best to get to the point and state what the protagonist saw, heard, or felt. In first-person and close third-person narratives, it's typically understood that the main character experiences the events taking place on the page.
Also, avoiding these constructions helps me vary sentence structure. It's an extreme example, but:
"She ran. She saw the wall looming ahead. She climbed over it. She felt grass crunch underfoot as she landed."
is less interesting than:
"She ran. The wall loomed ahead. She climb over it. Grass crunched underfoot as she landed."
Like lots of good advice, this looks painfully obvious in retrospect. And like many bad habits, my filtering* was an unsuccessful attempt to do something else right. In this case, I was trying to (1) include sensory details and (2) keep the narrative focused on the protagonist's perspective. Filtering diminishes the impact of sensory details and throws reader's out of a character's head, which I now know.
And knowing is half the battle.**
*For the record, it wasn't as severe as the example above. We swears it.
**Red lasers and blue lasers are the other half. Or so I hear.