For successful propagation you need to maintain the optimal growing conditions for your plants, and careful, managed watering is essential - too little or too much water can be equally damaging.
These Self Watering Seed Success Kits
make it easy for you to care for young seedlings correctly. They have an internal water reservoir and a growing tray supported above it. The growing tray is covered with capillary matting and fits into the water reservoir - allowing your plants to draw the water they need from the matting, so ensuring they are neither under nor over watered.