1. Plants that are weak, spindly and have pale leaves need to be moved closer to the light source.
2. Leaves that are very warm to the touch, showing burn spots, turning black, or dropping off are a sign that plants are too close to the light source.
3. Indoor plants need to be watered more frequently because of limited root space and the heat from the lights and home heating systems.
4. Most indoor plants need a minimum of 10-12 hours of light in the winter and 14-16 hours in the summer.
5. An automatic 24-hour timer to turn lights on and off is very convenient. For safety, I recommend a 3-prong plug timer that adapts to a 3-prong grounded outlet. A grounded, 3-prong timer (and extension cord) is required for most fluorescent fixtures. Check the maximum watt capacity on the timer. Do not exceed the capacity.
6. Turn plants in the window regularly to prevent them bending toward the light and growing lopsided. However do not turn a flowering plant in bud. Remember the sun coming through your window can be intensified by the glass.
7. White and light colored walls and ceilings reflect more light back to your plants.
8. Choose light fixtures with reflectors that have been engineered for plant growing as opposed to shop lighting, etc. Plant light fixtures are shaped to direct all the light downward, precisely over your plants. They are usually painted white to reflect light better.
9. Keep tubes, lamps and bulbs clean and replace as needed.

Space plants far enough apart so air can circulate in and around them. Make sure they don't shade each other.