Your poster should be a short, abbreviated version of your paper. It is not acceptable to print out your final paper and glue it on posterboard. There is no one way to create a poster presentation. You will be faced with some tough decisions about what to include.
Space is critical.
Therefore you must use a larger font than used in your paper. The minimal font size that you can get away with is about 20. Obviously, you will wish to use bigger font for higher level headings. Times, Times New Roman, or Courier fonts are strongly recommended. Use effective headings.