Grass doesn't root very deeply, so you don't have to dig down far - you're not preparing a vegetable patch. Just ensure that the ground is not rock-hard beneath the lawn. Aim for a firm, but not compacted, even surface, with good drainage from the top inch or so, ensuring that the lawn won't be under water after heavy rain.

Digging in organic material is not a good idea because it continues to rot and shrink, making the ground above uneven. Uneven ground means the mower misses the dips and scalps the bumps, which isn't pretty.

• Spray off (optional) an existing lawn or overgrown weedy area to kill off perennial weeds and make the area easier to dig.
• Dig the ground over when it is reasonably dry (if a lot of soil clings to your boots, it's too wet), removing perennial weed roots.
• After digging, rake the ground level, raking off larger stones as you go.
• Firm up the surface by treading the ground on your heels, shuffling up and down in one direction, raking the ground again, then treading again at right angles to the first direction, before raking level again. The treading produces a firm surface for the lawn; the raking provides a fine tilth for grass seed to germinate in and for turf roots to grow into.

Once the ground is prepared, the last job is to apply a slow-release balanced fertiliser (N:P:K ratio of 7:7:7) such as Rolawn's. Do this about a week before you plan to sow or turf, and incorporate it into the soil by raking (unless the rain does the job for you). If left on the surface, fertiliser can damage new roots.

Delay sowing or turfing until a dry day with mild and wet weather forecast - usually March/April or August - but don't rely on the calendar alone - a wet summer is ideal for establishing a lawn.

There's no need to water after sowing because the seeds will take up moisture from the ground, but if there is a hot dry spell after turfing, you may need to water if the turves begin to shrink away from each other. However dry the weather, the turves should take root - you can check by gently peeling back the edge of a turf.

Turf suppliers Rolawn have lots of advice too.