Surface tension is a result of a substance holding together with itself, so you would imagine that a substance with strong intermolecular forces (like water) would have a high surface tension. These molecules at the surface form a layer and you need a certain amount of energy to overcome and break the surface layer. When you heat something up, it adds energy, and that energy can overcome the surface tension.
You can also add things to the substance to interfere or disrupt its intermolecular forces. For example, water has a high surface tension because it is strongly attracted to itself. However, if you add alcohol, instead of water interacting only with other water molecules, it now interacts (less strongly) with alcohol, and the surface tension of the mixture will be lower.