Scarifying
Scarifying is when you rake your lawn to reduce the layers of thatch. Thatch is a collection of debris such as dead grass and old moss that can prevent water and fertiliser from getting through to the roots and soil.
Autumn is a great time to scarify as you can rake a little deeper than if you were to do it in spring when you would have to be more delicate due to the young growth.
Use a long tined lawn rake and be quite vigorous. The lawn will end up looking rather ravaged, but not for long – the grass will recover quickly and be more healthy as a result.