The feel and color of the soil should be used as a guide in watering indoor plants. You can't tell this by looking, so you have to feel the soil. Commercial plantscapers use small water adsorbant sticks poked in the soil to detect the amount of soil moisture. You might try using a porous toothpick. If the soil feels damp, don't water.
Plants differ in their preference for soil moisture levels.
Some prefer to be kept moist but not wet. They must have a relatively uniform amount of water in the soil at all times. These plants tend to have a fine root system that will die if the soil becomes very dry. Finally, there are some plants with coarse roots that are well adapted to dry conditions. Water should be at room temperature.