Identify the causes of the problem. Determine what pests eat, where they are coming from, and what kind of organism you are trying to control. The best way to get rid of pests is to not attract them in the first place. Cleaning up after yourself, shutting windows, and taking out the trash regularly are the keys to keeping pests out of the house. Just like with people, a healthy plant is less likely to get sick or be preyed upon than a weak plant.
Plants have defense systems just like animals.
Encourage your plants to protect themselves by keeping them strong and healthy. Be sure to take into account your specific climate. In addition to conserving water, this keeps plants from getting burnt by the noon sun which reflects off the water, or from getting stressed by cold if watered at night. In order to save yourself time and to stimulate root growth in your plants, water less frequently but for longer duration. Fungus growing on your plants is a sure sign that you are over-watering.