African violets make attractive houseplants, but have a reputation of being a little tricky to grow successfully. In fact as long as you provide the correct conditions the plants will thrive. The three requirements are moisture, temperature and light. Since the violets are native to East Africa you just need to replicate their local climate. I found this article on the University of Wisconsin Extension website which gives comprehensive information on growing these plants.

You can grow African violets successfully in your home if you provide moisture, temperature,and light conditions similar to those under which the plants grow naturally. This isn?t as difficult as you may think, even though the African violet comes from the coastal and mountain regions of East Africa. There the temperatures average 70 ??80 ?F and never go below 50 ?F or above 100 ?F. The plants flower profusely in the moist air and rich soil of shaded, rocky areas. In homes we can control heat, light, and moisture to give our African violets ?natural? growing conditions.
Soil and fertilizer
African violets thrive in a fertile, porous, well- drained soil. For a good soil, mix one part coarse sand or perlite, 2?3 parts loamy soil, and three parts organic matter?peat moss or compost. With heavy garden soils that contain a high percentage of clay or silt, mix in more organic matter and perlite or sand.Many garden soils contain insects and disease organisms; therefore, sterilize the potting soil mixture to kill insects or diseases that might hurt your plants. Commercial mixes are usually sterilized, and this information is printed on the bag. To sterilize your own potting mix, moisten it slightly, place it in a heat proof container, and heat it to 160 ??180 ?F in your oven. Maintain this temperature for 45 minutes. This procedure improves the physical structure in addition to
destroying insects, diseases, and weed seeds.

See more at the University of Wisconsin Extension
Image source: Richard Fraley