Organize where everything will have its place. A well organized classroom has places for all of the important items, such as paper, gradebooks, books, scissors, glue, markers, etc.
Paper, Paper and More Paper
Specifically, figure out where to put student papers that needed turned in, graded, and handed back to the students. In addition, decide where handouts will be placed for students who are absent. And, where will the piles of copies go before they are handed to the students?
Buy bins, baskets and folders to help organize the papers that quickly turn into a mess. I know this first hand, as I usually have every flat surface covered in some type of paper.
Learn How to Use the Grade Book
If your school is like most, it has gone to an electronic grade book. They are super tools, if you know how to use them. Some school districts automatically load student names and basic information for the teachers; however, if your school does not, this takes quite a bit of time.
Practice loading a "fake" assignment so that you can learn how to use all of the functions and keys. Check out how to weight assignments, set a grading scale and how to take attendance.
Make Basic Outline of Units for Semester or Year
Many schools have a curriculum map for each subject area and grade. Locate your specific curriculum map and plan your units accordingly. If the curriculum has not been mapped out for the year, then find out if your state has standards for your subject area. Use the standards and indicators for your content area to plan the school year. It also helps to talk to seasoned teachers down the hall too.