Determine the best method of storage (or combination thereof) for the material you plan to include in your portfolio. Since you will collect items over an extended period of time, use binders, boxes, clipboards, or plastic containers with lids, as appropriate for each set of materials. Label each item to make it easy to find when it comes time to assemble your portfolio. While the term portfolio suggests a singular presentation, a comprehensive teaching portfolio will probably actually require several storage vessels.