Water

Water as appropriate. Most people are afraid of underwatering, so they tend to water too much. Overwatering however is more responsible for plant death than underwatering.

Overwatering is also likely to create a good environment for pests and disease. It's best to let the soil dry a little before watering again.

Light

Put plants in the proper light. Next to water, light in the interiorscape is the most limiting factor. Most plants require more light than that found in homes and offices.

Some tropicals are well adapted to the interiorscape because in the wild, they grow under a canopy of foliage of taller plants. Use these plants for places where natural light is more limited.

Most plants will do well to be placed near a window provided that it doesn't get too hot or cold.

Soil

Soil should drain well. When watered and left alone for a week, the soil should be completely dry.

Humidity

Most tropicals require a lot of humidity. At least 70 % is preffered.

Temperature

70-75 degrees Fahrenheit at all times is optimum for nearly all indoor plants.