Mow regularly and continue adding clippings to the compost heap.
Use the half-moon edging iron, or a spade, to create a 7.5cm (3in) gutter around the lawn edge. This will prevent grass from creeping into the border from the main lawn.
Apply a high nitrogen summer lawn fertiliser to encourage a healthy-looking lawn.
Sowing new lawns or over-seeding dead patches can still be carried out in early May. Prepare the ground for sowing, by cultivating, levelling and lightly firming beforehand. Do not walk over or mow newly sown grass until it has reached a height of 5-7.5cm (2-3in), and then only give it a light trim at the highest setting.
Ensure new lawns (either from turf or seed) do not dry out during dry spells. Keep off them for as long as possible to allow establishment. Don't worry over a flush of weed seedlings in newly seeded turf. These will disappear once regular mowing begins.
Troubleshooting
If moss is a problem, choose a combined fertiliser and mosskiller when feeding the lawn.
Selective lawn weedkillers will kill the weeds but not the grass or any naturalised bulbs. However, be warned - they will kill wild flowers growing in the turf.