In spring, gently rake the grass with a spring-tined rake, taking care not to tear it. This removes winter debris and lifts grass and weed foliage for efficient cutting. Leave a pile to one side, for the birds to use to build their nests.
Once the soil is warm, sow bare patches. Fork the soil to break it up, then firm and level it before applying appropriate grass seed. Cover with fleece or polythene to keep the birds off and water regularly.
Your first cut should not be too short. Especially if a sunny day leads to a night time frost.
Throughout summer, leave the clippings every so often. As they decompose they release nitrogen, providing up to 30 per cent of the lawn's required nutrients, especially if you have clover growing amongst the grass.
If cuttings are long, add them to the compost heap (alternating with layers of brown stuff, such as straw, paper, or cardboard, otherwise they go soggy.) Or use them as a mulch over damp soil around trees, fruit, vegetables and flowers.
Discourage perennial weeds by digging them out regularly with a narrow trowel.
Why not leave some areas uncut? Mowing paths between uncut areas creates an interesting mix of order and adventure. You can also plant or sow flowers within the long grass, to attract pollinating insects. See Creating a Wildflower Meadow
In autumn, continue to aerate the soil to prevent moss.