Are you unsure about when to use then or than in your writing? Remember that then indicates a shift in time (e.g., I came to work, and then I went home), whereas than indicates a comparison (e.g., My dog would rather run off-leash than walk next to me). For example:
My grades are better this semester than last semester.
We're having dinner first and then we'll watch the movie.
Her choice of ice cream seemed unusual, but then I remembered that she likes chocolate better than vanilla.