Less is more! You might not expect it, but too much water is cause of death #1 among plants. So it's much better to water small bits more often instead of a whole splash. Roots may need enough water, but too wet soil will rot the roots and your 'green amigo' can't take that.
Before you get started with your watering can, it's a good idea to make sure the soil isn't still wet. You can do this by putting your fingers 2 cm deep into the soil. Does soil stick to your fingers? Then you know your houseplant is still provided for a while. Does the soil feel dry? Then pour some more! Simple as that.
It may sound strange, but many houseplants die because of too-much or too-little water. A good way to prevent this is to water a little at a time. Making sure that the soil isn't still wet helps ensure you don't over-water your plant!
Generally, it's best to water your plants in the morning. That way, both your plants and the water are cool, which is what they prefer. Don't forget that plants can get a shock from cold water, causing discoloration or leaf damage — so use lukewarm water whenever possible.