There are several things to be aware of for your tropical plants spending the winter indoors. First is good light.
I can provide most of my plants with very good light since I have both a sunroom and a greenhouse. However, for most folks getting adequate light to plants in the house during winter is difficult. Less light and generally dry conditions from our heating systems place stress on these plants.
Depending on the plant and its size, artificial light can sometimes be provided to help indoor plants by using florescent or other light fixtures. This often takes quite a bit of room and is something that many people cannot or do not want to do. Rotating plants to a bright window can help including in the garage if it is warm enough.
Likewise, the humidity level can be increased somewhat with humidifiers, by bunching plants close together, and by setting plants on trays of water – elevating the plants above the water so that they are not sitting in it. This also can be difficult.
Fertilizing and overwatering plants in winter are two of the most common mistakes. Because plants are growing slowly, if at all, they cannot utilize fertilizer and they do not need as much water.
Unless the plant is one that can thrive in the conditions in your house, stop all fertilization until late winter/early spring. If fertilizer is needed for some plants, use ½ or less of the recommended strength. Water only when plants are dry. If you forget to water, they will tell you they need water by wilting. For most plants, too little water is better than too much.
Weakened plants under stress are more susceptible to problems. The three most common pests I confront inside are fungus gnats, whiteflies, and