Step 1: Watering

Watering is only necessary in dry, warm periods. After about a week without rain, grass starts to turn yellow, so water before the problem gets worse.
Infrequent heavy watering is better than daily splashes. The minimum to apply is 9 litres per square metre (2 gallons per square yard).
The simplest method is to use a lawn sprinkler - the oscillating type is best as there is little overlap between adjacent areas.

Step 2: Feeding

Feeding encourages strong healthy growth and builds resistance to weeds, moss and drought. Use a distributor or spread by hand.
In spring, apply a general balanced fertiliser. You could buy a proprietary type, or use Growmore or an organic equivalent, at the rate of about 50g/square metre (2oz/square yard).
In summer, feed monthly with a high nitrogen fertiliser. Use a proprietary feed or a sulphate of ammonia at about 12.5 g/square metre (1/2oz/square yard). Dilute first and apply using a watering can to avoid scorching. Do not use after August.
In autumn, apply a general balanced fertiliser or one higher in potash to 'harden off' the grass before winter.