Gesneriads need bright light but not direct sun. They can easily be grown in an east to northeast facing window as well as under fluorescent lights. Some early morning or late evening sun shouldn't harm them but direct sun during the mid-day can cause burning to the leaves and the flowers. It is important they get adequate light as too little light leads to plants producing very large leaves and little or no blooms. You can also successfully grow your plants under a two tube 'shop light' fixture with daylight type bulbs with about 12-14 hours of light per day.
Gesneriads are heavy feeders so using a constant feed program is best. Simply add ¼ tsp of a well balanced fertilizer (e.g., 20-20-20, 15-15-15) to a gallon of water. Use this “fertilizer water” to water your plants. This provides a constant feed program for them.
Gesneriads prefer to be grown in cool conditions. Growing temperatures should remain between 55 and 75 if possible.
This seems to be where most people go wrong and lose their plants. Gesneriads can’t tolerate being kept too wet. If growing in a self-watering pot such as an Oyama pot, it is best to let the water reservoir dry out between waterings. You don’t want the plant to wilt before you refill the reservoir but a good “guide” would be to add water back to the reservoir about a day before the plant begins to wilt. One of the easiest ways is to pick up the pot and judge by the weight of it. Don't water unless the pot feels considerably lighter than right after you water it. You can also use your fingers to check the moistness of the soil. If the first 1/2 inch is dry it might need some more water.
Gesneriads have a vigorous root system which enjoy being grown in light/porous potting mix. A quality potting mix, such as Premier Pro-Mix or Sunshine 4, are excellent mixes and can be found at most local hydroponic stores or on Amazon.
Pots and Repotting
I have found Gesneriads do exceptionally well in self watering pots such as Oyama pots. I typically grow them in a 4”, 5” or 6” pot.
It is best to repot them into fresh potting mix every 4-6 months.