It is often assumed that setting up a bitmap at 300dpi is both necessary and sufficient to make every print job come out perfectly. The inherent flaw in this view is that it assumes that best print quality can be attained by using raster files (files composed on dots) rather that vector files (formula’s created using dots, lines, fillers and locations).
This view is perpetuated mainly by file size. Vector files are tiny. Raster files are huge. We naturally think bigger is better. It’s not. That said, vector program like illustrator (which save in formats such as .ai, and .eps ) have their limitations. For one they do not allow you to manipulate images properties or apply many of the effects at your disposal in non vector programs such as Photoshop.
We suggest you start in a program like Photoshop to get your artwork’s raster elements resolved and add all the vector elements in illustrator. If you are starting the process in Photoshop with the end aim in mind of printing some considerations are worth entertaining.
First off, avoid image file types designed for web applications such as PNG and GIF. For one these files are designed to display on screen and as such they both can’t be properly converted into CMYK (they only save in RGB and need to be converted to CMYK for print) and save at a below print quality resolution (72 dpi as compared to the 150dpi which is required).
Secondly, we suggest that you design to scale and start with the final size in mind. It is remarkable how often I receive monster files from designers who have designed a card to be printed the size of billboard or alternatively have inserted an image the size of card to be printed on a billboard. Just because your image properties read 300dpi it does not mean that your embedded image will be 300 dpi. The solution: set your artboard to size and then analyse the image itself. If when viewed at %200 your image is still relatively clear then you are in the clear.
When you are really unsure we do a print sample which you too can easily do. Clip an 8.5X11 portion of your image and run it on your printer. Even in black and white you should get a rough indication of the resolution and if it will stand up to the application you have in mind. That said, the assumption here is that your application is a large format commercial job. If not, or if you are doing paper print we suggest that your embedded image always be to scale and 300dpi.