Seeds should be started in flats or jiffy pots using a fine seed starting mix or potting mix.  You don't want to use a growing medium that has too much wood or mulch materials as they interfere with the germination process.

Pre-moistening the soil before planting the seeds will help keep the seeds at the intended depth for germination.  If you water the seeds after they are planted, the water will pull the seeds down too deep.  If this is the case a slight "tilling" of the soil with a fork or even a comb will often bring the seeds back up closer to the surface where they need to be.

Proper sunlight and water are critical.  You need to keep the seeds moist using a fine misting spray, again to keep the seeds from going too deep in the soil. If the seeds are allowed to dry out once they've been planted they will die!!

Seed flats need to be kept warm and soil temperature consistent.  They need to maintain a steady temperature of 65-70 degrees at night and warmer during the day.  One suggestion is to use a heating pad set on low underneath the tray or flat.

If the soil gets hard-packed or crusty you may need to gently till the top layer of the soil. This crust will slow or even prevent germination.

Planting seeds too deep will hamper germination.  Most seeds need only be planted 1/8" inch or less unless otherwise noted in the instructions.  Generally, the smaller the seed-the shallower it is planted, the bigger the seed-the deeper it is planted.