In addition to winwaed's answer...

A good technique for seedlings (not seeds) and potted plants, when you're not sure about how much to water, is to bottom-water. Assuming the pot has drain-holes in the bottom, place the pot in a pan of water an inch or so deep (less for small pots) for a few minutes. Be sure the water can get in - that both surfaces aren't flush. The soil will wick up the water, and there's no chance of over-watering. You want the water height to be such that it will get into the pot and wick up, but the height of soil in the pot that's below water level is small relative to the size of the pot.

With seeds and seedlings, if you over-water the surface you risk getting "damping off" and other problems caused by mildew and mold. You need damp soil, but drier air above it. It's tempting to cover the pot with clear plastic or something to keep it from drying out - don't do it!

In addition to winwaed's answer...

A good technique for seedlings (not seeds) and potted plants, when you're not sure about how much to water, is to bottom-water. Assuming the pot has drain-holes in the bottom, place the pot in a pan of water an inch or so deep (less for small pots) for 5 or 10 minutes, or until the top of the soil is damp. Be sure the water can get in - that both surfaces aren't flush. The soil will wick up the water, and there's little chance of over-watering. You want the water height to be such that it will get into the pot and wick up, but the height of soil in the pot that's below water level is small relative to the size of the pot. The only case this will cause over-watering is when an extremely heavy, humus-heavy potting soil is used.

With seeds and seedlings, if you over-water the surface you risk getting "damping off" and other problems caused by mildew and mold. You need damp soil, but drier air above it. It's tempting to cover the pot with clear plastic or something to keep it from drying out - don't do it!