Cut cardboard milk or juice cartons in half horizontally to plants things like sweetcorn and beans. When you are ready to plant out, cut away the sides of the carton with a pair of scissors and slide the seedlings into place.
When using seed trays or pots that have been used before be sure to disinfect them before use.
When sowing fine seeds, you can mix with sand to make them easier to sow.
When watering tender seedlings use water that has been allowed to warm up in somewhere like a greenhouse.
Label your seed trays/pots and place them in a warm sunny spot. If seedlings get insufficient light they will become tall and spindly or "leggy".
Seedlings should be kept moist, but not too wet and should be watered from the bottom.