I think that the main reason people kill indoor plants is poor watering practices. Many people are prone to watering too little or too much, and these extremes kill plants. Here’s how to water a houseplant well:
1. Be sure that there is a deep saucer or a tray under all of your plants. If you use a decorative plate it might be pretty, but when you water the plant well the water that drains will overflow that plant fairly quickly and this will lead to you watering less because you don’t want dripping on the floor. So be sure that the saucer under every houseplant is large enough to accommodate a good amount of excess water as it drains out.
2. Water the plant when the pot feels light when you pick it up, or when the top of the soil feels dry. It’s fine to be on a once-a-week schedule but this might not be enough for some plants or some households. The warmer your house, the more frequently you’ll have to water.
3. When you water a houseplant, give it enough so that the excess flows into the saucer below. Let that plant sit for five or ten minutes while you water your other plants, then come back to it. If there is only a small amount of water in the saucer, water the plant again. Let as much as ½ to 1” of water accumulate in the saucer below and let the plant sit in that overflow for three or four hours.
4. After that period of time, go back and soak up much of the remaining water in the saucer with an old bath towel or suck it up with a turkey baster. You can leave a little bit of water in the saucer, but not more than ½ inches deep.
5. Wait until the plant is dry again, and repeat from above.
Boot trays make good under-plant water catchers. I got the metal one above at our local Christmas Tree Shops.