Answer: Browning at the tips can be a sign of several different problems, you are right. Your tree needs to be kept as bright as possible. It needs high humidity during the indoor heating season and a relatively cool room temperature (this also helps with the humidity.) Browning leaf tips are a common sign of lack of humidty/too hot a location.
Keep it away from drafts, both hot and cold.
You would water when the top of the soil is quite dry, so the tree does not stay saturated or sopping wet, but it should not dry out completely. When you water, water thoroughly and make sure the water is soaking into the soil and not running out between the edge of the soil and the pot. After watering, allow the excess to drain out and then empty the drainage saucer so the pot is not left sitting in water.
Browning at the tips can also mean it has been overfertilized or there is a buildup of fertilizer salts in the soil. Stop fertilizing in the winter months, then use only the amount recommended on the label of whatever product you use. (Slow release or liguid soluble.)
Finally, check the foliage and stems carefully for signs of pests such as scale insects.
You might find the following article helpful as a general care guide. You may need to cut and paste the complete url into your browser to make it work correctly.
I hope this helps you troubleshoot.
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