Posted: 02/05/2017 at 13:07
Different seeds have different needs. Some like light, some don't, some like heat, some don't, they all need moisture but not drowning, some don't like root disturbance and need to sown very thinly in plugs so they can be potted on with no grumpng.
Generally speaking I find it easiest to sow in module trays filled with seed compost for small seeds and small pots for bigger seeds such as squashes and beans.
A lot depends on what you have sown but I think you need to let yours grow on till they're at least an inch or two high and then lift each clump out gently with a pencil or an old table fork. Holding them by their leaves - ever the stems - gently separate them and put each one in fresh compost in a module or a small pot. Firm them very gently so as not to damage the stem and water from below by soaking in a tray.
More info on seed sowing from the RHS here - https://www.rhs.org.uk/advice/profile?pid=501 You can often find specific info on reputable seed company websites - seedaholics, plant world, Chiltern if you google the name of the plant+seed.