Thes notes make the assumption that you have access to a wide format printer and you want to end up with a poster which is 44" wide x 68" high.
An effective poster is one that is easy to read, clear, concise and aesthetically pleasing. The following checklist will help eliminate any possible mistakes in the poster generation process.
Typical sizes include the following: 36" x 48"; 36" x 60"; 44" x 56"; 44" x 68"
However, Powerpoint will not permit sizes larger than 56". So the trick is to make a poster which is 34" wide x 22" high and print it at 200% to output a poster which measures 68" high x 44" wide.
Slides sized for: Custom
Width = 34"
Height = 22"
Slide Orientation = Landscape
Unless you are using a poster template, always start with a new blank presentation with a blank layout - without anything - not even a title.
When placing an image on the poster from another software application, DO NOT use copy & paste and DO NOT drag & drop no matter how convenient. Instead, use the Insert -> Picture -> From file menu item. This will guarantee that the imported file is properly filtered by PowerPoint.
The best choice is to insert TIFF or PNG image formats and to import the file sized for the space it will be inserted into. JPEG and GIF formats will work, but be aware of the distortions produced when you manually resize the graphic in Powerpoint using the inage drag handles. Try not to use GIF for files containing text. Do image editing in Photoshop or Canvas before inserting final graphic into Powerpoint file. Web pictures are usually unreliable for printing (low-res, 72 dpi). Try to capture or use a source which is > 300 dpi. However, bear in mind that higher resolution = larger filesize.
Make sure that the color scheme selected is clearly legible from a significant distance away. Keep in mind that too much color can be a distraction for the reader. Try to avoid using similar colors for both background and font colors. For example, use dark blue backgrounds with yellow fonts to allow for high-contrast and easy-to-read posters. To change a background fill, select Format->Background.
Assuming that you are working with a PowerPoint slide size of 34"w x 22"h and it looks fine on your screen but when you get it back from the printer with the size you requested which is 68"w x 44"h all the images look pixelated or distorted. This means that your inserted images were not at a high enough resolution. Before sending the above a file to a printer zoom in the slide at 200%. If it looks pixelated on your screen it will look pixelated when you print it.
Avoid non-standard fonts, instead, rely upon universal typefaces: Times New Roman, Arial, Helvetica and Symbol [Latin-1 subset] are recommended types and are available on both Mac/PC platforms. If you use a font which is available only on the Mac and show / print your presentation on a PC chances are you'll end up with strange characters or boxes.
Suggested font sizes are: 20 - 28 for main body text; 36 - 48 for main headers and captions; 54 - 72 bold for titles. Of course, this will vary depending on the amount of text and sizes of your images.
When ready to print the poster, make sure all objects in the file are ungrouped. Then print a normal 8" x 11" version of the poster by selecting the File -> Print -> Scale to fit paper menu item. If it's legible then uncheck the scale to fit box and save the file.