The #1 killer of houseplants is over watering. Theres not much a gardener can really do for houseplants, so they provide TLC by watering every chance they get. Plants take in air through their roots and if the soil is constantly wet, they cant do this. Instead youll be encouraging root rot, which can kill a houseplant.
Dont automatically water all your houseplants on a schedule. Check to see if the soil about 1" below the surface is dry, before you water. When you do water, water thoroughly. Water until you see the water coming out the bottom drainage holes. This procedure will help brown thumbs who underwater as well as those who water too frequently.
Don't let your plants sit in water either. If you increase the humidity around your houseplants by placing them on a tray of pebbles sitting in water, make sure the water level is below the bottom of the pot.
If will also help if you use a light potting soil instead of garden soil, which tends to be heavy and doesn't allow water to drain through.