Water the plants only when they need it. Over watering creates more problems than any insect or disease. Check the top inch of the soil. If it is still moist, the plants do not need to be watered. Once the top inch of soil dries, water thoroughly, allowing the water to drain out the bottom of the pot.
African violets bloom best when crowded.
The leaves should hang above the soil but not touch the edge of the pot where salts collect that can injure the plant. If leaf stems lay across a wet rim of the flower pot, they may rot. To prevent this, cover the rim with paraffin or aluminum foil. African violets do best in bright, indirect light. Place them in a room that receives about 12 to 15 hours of light a day.