First of all, you should prepare a portfolio of best works, either in an electronic, or in a paper form. Every responsible designer serious about his job search has one. It can be simple, but it should be nice. Do not economize. Use quality printer and colors, so your works look good on the paper.

Such a portfolio should include also a goal of each project, your target audience, and programs/techniques you used to complete it. It is good to have few copies of your portfolio, so you can leave one to the interviewers (at least for temporary time).