Start with the rug, not the cleaner
A synthetic rug and a hand-dyed wool rug can react very differently to the same liquid. Read the label and note any previous cleaning before treating a stain.
On a fresh spill, blot with a clean white cloth from the outside inward. The aim is to lift liquid, not push it into the backing.
When to stop home treatment
Stop if colour transfers onto the cloth or the stain spreads. Do not saturate the rug. Moisture caught beneath the surface can create a second problem.
A specialist is the safer route for delicate fibres, valuable rugs and unknown old stains. A good cleaner will want to know what the spill was and what has already been used.
What to bring when asking for help
Share the care label, a clear photograph, the approximate age of the stain and the rug material if known. Those details are far more useful than a generic online cleaning recipe.