Over watering flowers is a common problem. Most of the time, the gardener simply over-estimates the amount of water the plant needs. This happens a lot with indoor plants because the water does not evaporate as quickly indoors. You can tell a plant is being over watered because it will have a wilted appearance but the soil will be moist and mucky. Sitting in an overly wet soil will prevent the plant from developing a good root system. Luckily, you can revive an over watered plant.
Allow the soil of your plant to dry out slightly. The top 1 inch should be dry and beneath that, the soil should be slightly moist. Don't allow the soil to become overly dry--a plant should need to use its roots to find water. Allowing the soil to dry will help revive the plant.
Check your plant every day or two. When more than the top 1 inch of surface soil is dry, water again. Generally speaking, plants need 1 inch of water per week. However, it is best to use your own judgment when watering because of the variables. Consistent watering will prevent the plant from wilting.
Water your plant slowly to prevent soil erosion. If your plant is outside, try watering it in the morning instead of the afternoon or evening. The heat of the afternoon may cause too much evaporation and the cool wetness in the evening may cause fungus to grow.
Stop watering when the soil looks moist but not muddy. Check under the top layer of soil to make sure the soil is watered all the way through.
Stick plant fertilizer spikes into the soil. Read the manufacturer's directions to find out how many to use and how often to apply them.