Remove stains in your carpet with a stain remover or by blotting up fresh stains with a rag. After blotting the stain, flush it with cold water and blot it again until the stain is gone.
Cut off any loose threads, fuzzy areas or other snagged pieces with a pair of scissors. Cut close to the shag carpet, and keep your cut even with the rest of the carpeting.
Rake your carpet with a carpet groomer before vacuuming in order to remove debris and loosen dirt.
Vacuum your shag carpet regularly to keep dirt and debris out of the long fibers.
Clean your carpet with a steam cleaner, or hire a carpet cleaner to clean it. The hot water will loosen dirt, and the extraction device will remove it from your carpet resulting in a brighter, newer-looking carpet.