Begin with the packet
Read the sowing window, depth, and spacing before opening the packet. Those three details prevent most early problems. If your climate differs from the packet’s region, use local frost dates as the better guide.
For a first attempt, choose fast, forgiving seeds such as radish, lettuce, basil, nasturtium, or dwarf beans.
Use a simple growing mix
Fresh seed-starting mix holds moisture while leaving room for air. Fill clean containers with drainage holes, dampen the mix first, and sow only as deep as the packet suggests. Very fine seed is often barely covered.
Label the pot when you sow it. Memory becomes surprisingly optimistic around a tray of green shoots.
Warmth first, light next
Most common garden seed germinates best in gentle warmth. As soon as shoots appear, move them into the brightest suitable position you have. Turn windowsill trays daily so stems grow evenly rather than leaning.
Water by checking, not scheduling
Touch the surface. Water when it begins to feel dry, using a fine rose or watering from below. The mix should stay evenly damp, never swampy. Good airflow and sensible spacing reduce mould and weak growth.
When seedlings have a few true leaves and outdoor conditions are suitable, acclimatise them gradually over about a week before planting out.