At the very least, this is one thing you must do. Loglines are typically talked about in terms of pitching a screenplay and this often gets a logline confused with a tagline (a marketing tool.) However, the logline is an indispensable part of pre-writing for the simple fact it gets you thinking about the most important parts of your story.

The goal.
The conflicts.
and The characters.

The best loglines I’ve seen, and the ones that best serve the writing they are representing are loglines with irony. Irony IS conflict, and there is half your battle.

For example: A kid hating paleontologist must work with two children to escape an island infested with man eating dinosaurs. A bad pitch rendition of Jurrasic Park, but it describes the protagonist succinctly, it describes the conflict of both dealing with the children (and most likely not very well) along with the conflict of the dinosaurs and the goal of getting off the island.

This is a description by Blake Snyder:

“On the verge of An Emotional Starting Point Needing Change, a Flawed Protagonist Breaks Into Act Two; but when the Midpoint happens, he/she must learn the Theme Stated, before All Is Lost.”

Some more formula examples.

“An ADJECTIVE (describing a defect that must be filled in, your B STORY) NOUN (protagonist) must ACTIVE VERB the ANTAGONIST before THINGS ANTAGONIST OR ANTAGONISTS WILL DO TO STOP PROTAGONIST FROM REACHING THEIR GOAL.”

“Who is the Protagonist? (describe with adjective)
What do they want? (goal)
Who is keeping them from it? (and how.)”

Aim for 40 words or less to keep it succinct and exercise the superfluous writing elementary and high school creative writing classes ingrained in you.

Write and rewrite your logline, use those ideas that you didn’t plan out but started scripting from page one.  You may find you need to change some things!  This will get you in the habit of thinking with the goal in mind and the conflicts you need.  Remember, a story is meant to be an exaggeration of real life but still relate-able.  It’s the oldest form of sharing wisdom.  The parable.

After all, in your day to day, you don’t just walk outside and stand there till you figure out what you want to do for the day.  You decide to go to the grocery store, or hang out with friends.  Every slow person, every stray animals, every incompetent employee you encounter before you reach that goal is a conflict.