A clean persian rug makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.
Vacuum the rug without the beater bar. Beater bars damage the fibers and weaken the foundation.
Dab a hidden area with a damp white cloth. If color transfers, hand cleaning may damage the rug -- consult a professional.
Mix a small amount of mild dish soap with cold water and a few drops of white vinegar.
Dab stains with a soft cloth dipped in the solution. Never rub or scrub -- it damages the fibers.
Blot with a clean dry cloth to absorb moisture. Air dry the rug completely before walking on it.