The seed packet should indicate this. Otherwise, seeds should be planted at a depth equal to twice their diameter. If they are planted too deeply, they may not germinate. A spray bottle with a fine mist is handy for wetting the surface without washing away tiny seeds. Waiting even a couple of days can cause the seedlings to stretch so much that they will never be as sturdy as they should be.
Fluorescent lighting is ideal.
Keep the lights on about 14 hours every day. Then a good southern or western exposure window. Warmer temperatures can cause rapid, weak growth. Seedlings generally do not need fertilizer until they are transplanted from the seed tray or when they have 2 sets of true leaves. They are fed from the reserves from the seed itself up to this point of growth.