Regularly mow lawns to keep them in shape - removing 'little and often' is the key to a good quality sward. Continue cutting lawn edges with a half-moon edging iron to ensure they are neat.
Mow pathways through areas of long grass to allow access to other areas of the garden
Add grass clippings to the compost heap in thin layers (too much grass all at once is likely to be very wet and poorly aerated, resulting in smelly slime rather than compost).
Apply a high nitrogen summer lawn fertiliser if not done last month to encourage a healthy-looking lawn - always follow the manufacturer's instructions carefully, as any over-use or runoff can cause water pollution.
Move garden furniture and other objects regularly to allow grass to recover and prevent yellow patches.
Ensure new lawns (either from turf or seed) do not dry out during hot weather, as turves will shrink if allowed to dry out, and fail to knit together.