Keep the soil moist but not wet, tending more to the dry side at the top of the container. Nothing worse than a seedlings roots not having enough oxygen to get them pumping.
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Water will do for now, don't get all anxious about pouring on fertilisers just yet. That can wait until some true leaves start to open up.
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If you can try and water from the bottom up. Simply placing the container into a bath of water a couple of inches high works good. Bottom watering benefits the plants by way of encouraging the roots to head down to where the water is, thus the root mass grows faster.
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Pour light on them, either with cfl's or leds. Although a window sill can be used just as easily if the light is there most the day.
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Give them a break from the light if under artificial lighting. Seedlings tend to like a dark period and will often show a growth spurt during the dark times. Think 12 on 12 off or 18 on 6 off.