It depends what sort of image you are looking for, but I have heard that Capelli near the Cambridge estate (on the Kingston Road) is reasonable and very good for precision cut and colour. I heard about it just by asking someone, cos their hair looked really good. There are some good independent shops in New Malden which are cheaper than Kingston...it's a bit out of the way but there is a shop called Peter's in South Lane, New Malden, and the owner was trained by Mr Teasy Weasy the original stylist. You can get 20 per cent off there with some versions of the local Arts and Leisure brochure.
Titi's (titter ye not) in Coombe Road, New Malden is a Korean hairdresser which is really professional and they often have promotional prices.