Some teachers underestimate the time it will take to plan quality lessons, along with mapping out how they will cover content for each semester and by the end of the school year. Take the time needed to get to know the curriculum.
Plan with other teachers in the same grade/content, or across grade levels instead of in isolation. Doing this saves time and supports the sharing of ideas and resources between teachers.
Over plan. It is easier to take things out of a plan than to ad lib and add less than quality experiences to a plan.