There are some options in Illustrator that can catch you out. This particular one could cost you dearly if a job goes to print after overlooking this crucial option, resulting is a fuzzy/compressed and pure ugly rendering on the effects you added to your design. What we're talking about here is Illustrator's Document Raster Effects setting.
Let's say you have an object within Illustrator, and you add an Outer Glow, Drop Shadow, Inner Glow or basically anything from the Stylize menu.
Now the problem comes when you export that file as either an AI or EPS, Illustrator will convert those effects into a raster format but the default setting for this raster conversion is set to 72ppi, which will look hideous on any litho or large format print. You do at least receive a warning message in the dialog box upon saving, but this could easily be overlooked or you may not know exactly what it means.
As an example, if you went ahead and saved your file regardless of the warning, check out the detail on that effect you added. Pure ugliness! Ok, this example has been zoomed in slightly on screen with Photoshop, but the final printed version would look just as bad.
So, how do you fix this? Go to Effect > Document Raster Effects Settings…
In the options box, select 300ppi. Alternatively 150ppi can be sufficient for large exhibition graphics.
Now, export your file and notice there is no longer a warning message. Take a closer look at your file and you will notice a nice smooth effect with no dirty compression.
What next? You should remember to always check this option before exporting your artwork for print. However, if you tend to work on many print projects you can actually alter the CMYK Template file within the Illustrator program files to select 300ppi as default. Afterall, if you're creating a CMYK file, chances are it is destined for print rather than screen! - Why Adobe doesn't make this default as standard I don't know.