Overwatering is the single biggest killer of houseplants. We call it ‘killing by kindness’. You should only water plants when the surface of the compost appears dry.
I always recommend the standing water technique. Instead of pouring water onto the compost, stand the pots in a tray or sink in an inch of tepid water. Leave for five minutes, allow to drain and put the pots back. This lets roots take up only what they need without drenching the plant.
Or you can plunge the pots into a sinkful of tepid water and hold there until no more air bubbles appear. Then allow to drain as before.
If you have houseplants that like humid conditions, such as orchids, keep them in the bathroom. Or fill a saucer with pebbles and cover with water. Sit plants on the saucer, so they get the humidity without waterlogged roots.
You can also mist houseplants with spray water. It adds to the humidity and is welcomed by plants from tropical climates like orchids and poinsettia.
If you get out in the garden, remember to spruce up your containers too!