Write your philosophy of education. At first this may seem unrelated to building a portfolio, but clarifying your educational philosophy before building your portfolio will keep your portfolio from becoming what experts call a "steamer trunk" of unorganized and irrelevant material.
Identify the relevant standards, audience and context. Dr. Helen Barrett, an expert on electronic teaching portfolios, recommends teachers begin developing portfolios by linking student goals to written standards. You could also start with your philosophy of education, using those beliefs to drive your portfolio. You should also identify your portfolio's purpose and primary audience. Portfolios meant for job hunting might look different than those intended for tenure review.
Choose the types of content for your portfolio. Don't trap yourself thinking "I have to include this great lesson." Ask yourself: What aspects of your teaching do I want to showcase? Determine basic types of content first, and find specific pieces of content later. Whenever possible, link this content to specific parts of your philosophy of education.
Pick an electronic medium for your portfolio. Probably the most important decision you'll need to make here is whether your keep your portfolio online on a website, or offline on a computer disk or CD. While you'll organize them basically the same way, online portfolios have the advantage of what Vanderbilt University's Center for Teaching calls "increased accessibility." Putting your portfolio on the web allows many more people to see your portfolio, and lets you share it by simply giving people a web address. However, online portfolios are much more public than offline portfolios. If you're not comfortable having your teaching materials and contact information online, build your portfolio off-line using any program that supports hyperlinking, such as Microsoft Word or Adobe Acrobat.
Gather and analyze materials. Remember what you put in your portfolio may not be as important as what you say about it. For example, portfolios created for National Board certification severely restrict the amount of pages of student material, but allow much more space for teachers to analyze student work.
Organize your work. Begin by creating a table of contents. If you're creating your portfolio offline, build a hierarchical folder system to hold all your files, and put your table of contents in the top folder. Then, for both online and offline portfolios, hyperlink from your table of contents or start page to the different portfolio entries. Don't just organize vertically---take advantage of hyperlinking to show you think about teaching in non-linear ways. For example, link key words in your philosophy of education to content that represents those beliefs.
Evaluate your portfolio and revise it as needed. Re-read your philosophy of education and ask yourself: Does this portfolio reflect the beliefs I presented? You may also want to use a rubric for electronic teaching portfolios such as the one developed by Joan Vandervelde at the University of Wisconsin-Stout.