Start with new peat trays with detachable cells. Or reuse old nursery cellpacks (clean and disinfect used materials with a 10 percent bleach solution before use). Peat trays are biodegradable, so cells can be planted directly in the ground when it's time to transplant.
Use a lightweight soilless seed-starting mix -- a combination of peat moss, vermiculite, and sometimes perlite. It will drain rapidly and encourage seedlings to form a strong root system. Gently tap to firm the seed-starting mix, then moisten thoroughly.
Follow seed packet directions, which will tell you when to start seeds and how deeply to plant them, depending on climate and species. If sowing tiny seeds, fold a small piece of cardboard in half and use a toothpick to direct seeds into the cells of the tray.
Care and Transplanting
Put the tray in a warm spot within 3 to 4 inches of fluorescent lights kept on 14-16 hours a day. Water with a pump sprayer to avoid disturbing seeds. After seedlings develop their second set of true leaves, feed weekly with a water-soluble fertilizer (diluted to quarter strength). Transplant according to seed packet recommendations.