One of the easiest and best things you can do for your plants is to water them with distilled water. Normal tap water is full of chemicals and minerals that are harmful to plants. Well water usually goes through a water softener, which uses salts that are also bad for plants. Distilled water is pure and free of all additives, so you don't have to worry about what you are feeding your plants each time you water them.
Follow the watering directions for your specific plants. Generally, if soil stays slightly moist at all times, plants do well. Some plants, however, require heavier or lighter watering.
Fill a watering can with distilled water at room temperature. Very cold and very hot water can damage roots and kill a plant.
Pour the water into the soil surrounding the plants at a slow, steady pace. The water should be added at the same rate that the soil soaks it up. If the soil looks muddy at any point, you are either adding the water too quickly or you are over-watering. Adjust your application as necessary; continued over-watering can stunt or kill plants.