Assemble your material into a strong structure.
Once I read a book of film reviews and the main complaint was, “Good idea, but runs out of gas.”
Fix this with a strong structure along the lines of:
Prologue brief opening sets atmosphere
Act 1 Establish setting, characters and situation
Act 2 Develop characters and situation
Act 3 Accelerate the pace of story
Act 4 Complicate matters - the plot thickens
Act 5 Resolution build to climax and release
Epilogue quickly tie up loose ends