One of the most common gotchas we see in images and prints is the presence of spots. Regardless of the source such as dust on the sensor, every photographer should spot check their images before print, upload, email, delivery, etc. There are very few things that scream "lack of attention to detail" like spots in a finished image. At Light, we recommend spot checking every image at 100% or 1:1 view.
The best technique we have found to locate your spots is to use the Hand tool or a version of the Hand tool (other software) to slowly scroll through the image. Human eyes are very keen at detecting movement and this can help us find our spots. Many spots are very challenging to see on bright monitors when the photographer stares at the image. When you slowly scroll the image, dust spots appear to be moving against the background image.
This technique works extremely well. If you want to confirm a dust spot, wiggle the image with the Hand tool and the dust spot will jump off the screen at you. There are many instructors and photographers who recommend jumping through the image via keyboard shortcut. This is not nearly as effective as the scroll/wiggle method. Once you find your spots let the retouching commence (in a non-destructive manner, of course.) A common error with this method is to lose track of where you are in the image as you scroll. Use the Navigator to keep your bearings and you will easily check the entire image.