Non-oil Liquid Stains
Blot the stain immediately with a soft dry cloth. Don't rub with the cloth as that could cause the substance to sink deeper into the leather. Just blot at the stain until the cloth absorbs all or most of it.
Combine 1/4 cup dish detergent with 1 1/4 cups cold water in a container. Mix them together well. Dampen the cloth with this mixture. It should scarcely be wet. If you make the cloth too wet, you could risk creating water stains on your leather.
Dab at the stain with your damp cloth. The stain should start to vanish as you do this. Press another clean, dry cloth against the surface of the stain to absorb the moisture. Allow it to air dry.
Oil and Grease Stains
Place a clean paper towel over the area. Press down. Lift the paper towel and place a clean spot over the stain and repeat a couple more times.
Pour corn starch over the entirety of the stain. Sprinkle enough corn starch over the stain that it covers its complete surface area. Do not rub it in.
Allow the corn starch to rest on top of the stain for around four hours. After four hours, when you brush it away, the oil or grease stain should be gone.