You can get lots of information on the subject of defragmentation in the following articles:
Best Practices
There are a few best practice recommendations to outline from the start.
Clean Up: Before you can organize, it is always best to do a quick clean up. This is also true with your Hard Disk Drive (HDD). If you stop to think about it, the defragment process works to organize scattered data caused from installing, modifying, and deleting files and software. Before doing a defrag is the best time to do a quick removal of junk items including files in the recycle bin, temp files (unwanted items that are created as temporary storage), outdated cache items, log files, and more. Continue reading...