Most houseplants need watering "about" once a week. Each plant will differ depending on its maturity, what kind of pot it is in, where the plant is placed in relation to sunlight/heat/circulating air, and what kind of plant it is. Plants placed in windows will obviously dry out faster than those exposed to little direct sunlight.
For best results I suggest you set a regular watering routine. Creating a routine will also help you remember when to water (or not). We check all our houseplants twice a week (Sunday and Wednesday) however, Sunday is our designated watering day. Some of our plants could easily go two weeks or more without water, but it is easiest for me to do them all on a consistent day rather than remember individual schedules (because that is not happening).
Check by looking to see if the soil looks dry; then put your finger into the soil about an inch (to the first joint) to see if it is moist. Plants should be allowed to slightly dry between waterings, but don't let them wilt as that can be stressful for you and the plant. Hanging plants are my favorite as the best way to tell if they need water is to simply pick it up. To water correctly, pour enough water into the pot so that some comes out of the drainage hole. If your planter does not have a drainage hole, less water each time but more frequent watering is best. (Be sure to have stones or something in the bottom of a drainless pot). Discard the extra water. If the plant was very dry, water it again in about fifteen minutes. Don't let any plant stay constantly wet from standing water in the saucer.
Keep in mind that more plants die indoors from too much watering than from too little. When in doubt, water less. But if a plant begins to wilt, you’ve let it dry out too much.