Check your plants regularly for signs of stress, pests or disease. Remove dead leaves and flowers as they occur. The key to success is simple - find out where your houseplant originates from, and try to provide those conditions as best you can. Or choose houseplants that are suited to the conditions you have in your home. Don't panic if leaves or flowers drop, but treat your plant normally and wait until it has settled into its new spot.
Some plants also respond to changes in routine by dropping leaves.
Continue to look after them as normal until they recover.