Please check the weather in Delhi before you travel.
If it is too hot then please wear cotton clothes , sildenafil preferably full sleeves to avoid any sun burns and have something to cover your head like a cap or a scarf. Use sunscreen and have sun glasses. Full sleeves and pants also help you deal with mosquitoes.
Travel during rains is a mess as most places are either flooded or full of muck. Please wear lowers like a capris, avoid long pants. carry bags and clothes that are fast dry and water proof.
Shoes should be weather proof and comfortable. If you looking to shop in old Delhi and especially for fabrics then I have noticed that a slip on shoes work best as you will be required to take off your shoes outside most shops before you enter. A lot of my guests find it uncomfortable to tie laces as there is not place to sit while you wear your shoes.
Winters in Delhi are very comfortable and you can wear almost anything you are comfortable with but do wear slip on shoes if you plan to go to shops in old Delhi