From early September lawns will begin to grow quickly and will need a dressing of a specific lawn fertiliser, if it was not applied in August. The fertiliser will not only improve the grass on top but encourage new roots, which will assist in the prevention of drying off in summer.
Neutrog's 'Sudden Impact for Lawns' is an excellent product for re-juvenating lawns. As soon as weed seedlings appear use a lawn weeder before they get too big. If there are still some older weeds like Cape Weed in the lawn spraying twice at a months interval shopuld be successful. Alternatively they can be dug out and then the affected area can be reseeded.
Mow regularly but do not scalp the grass which can cause drying out and later bare areas. Mow in different directions each time.