Hi
Welcome to New Delhi. Depending on your budget, you have a variety of shopping options. C Block Market in Greater Kailash I has some exclusive shops with excellent stuff. One such shop is L'affaire.
If you are looking for good stuff at nearby locations, you can try Ahuja Vastra Bhandar in Govindpuri. For great sarees from all over India, you can try the Handloom Exhibition near Market no 1 in C.R.Park.
Lajpat Nagar of course has a good variety. You can get quality stuff at Ritu Wears, V Mart, and Chun Mun. Then there is a big Westside Store (a TATA company) beside the Lajpat Nagar Police Station. You can buy everything from crockery to garments at Westside.
Happy shopping.