limit the search to a subcategory or series of subcategories instead of searching all of the disc volumes at once.
it's recommended that you avoid searching in the System folders, especially if you don't have a good working knowledge of the Mac OS X operating system and its associated files.
If you use Apple's Time Machine backup software, it's recommended that you do not search a Time Machine backup volume, or delete files contained on a Time Machine volume. Deleting files from this location will impact Time Machine's ability to restore your computer.
While DupeZap is capable of searching any mounted disk, keep in mind that doing so will be considerably slower than searching the computer's internal hard drive.
It helps to know in advance which items you will be targeting as part of your search strategy. Are you trying to clean up a disc with a particular file type in mind? Do you want to remove empty folders?
Do you want to clean the database of one of Apple's applications?
A series of common Search Kinds is presented, including Music and Images. Clicking the triangle icon beside a Search kind will expand it, giving access to search options; you can choose one option via its radio button, select the search location(s) by clicking on the check box beside each location to be searched, then click the Search button.

You'll see a search progress indicator, and if there are items that match the chosen search kind, DupeZap shows the items to process, a second window will open showing the search results.
IMPORTANT: DupeZap cannot tell the difference between an original or a copy, so once you have the search results, you must choose the items to remove/manage. To identify which items must be managed and which left alone, you can start by reading the next step.