Apart from a hired car, the best way to get around New Delhi is by black-and-yellow taxi or radio cab service. Most hotels and restaurants will gladly call you a cab, and major markets and tourist attractions usually have a taxi stand. Most drivers speak a little English. Tell the driver where you want to go and make sure he turns on the meter before you set off. If he insists the meter is broken, get out of the car and find another cab. Most taxi drivers are honest, so it's not worth dealing with one who isn't.
The ubiquitous green-and-yellow auto-rickshaws are a good way to see the city from a different angle. But they aren't for the faint of heart, as the drivers zip through traffic at breakneck speed. Three-wheeled auto-rickshaws, known locally as "autos," are half the price of taxis and roughly half as comfortable—except in summer, when the open-air breeze keeps you cool while taxis trap the heat horrendously. The problem is that auto-rickshaw drivers refuse to use their meters (here they really often are broken, as the drivers deliberately break them), and if you look even remotely new to Delhi they will quote absurdly high fares. A trip around the corner costs Rs. 30, and a trip across the city should never cost more than Rs. 200. Government-run booths for prepaid auto-rickshaws can be found at Connaught Place, Basant Lok, Dilli Haat, and the Community Centre in Saket, among other places. Try to have exact change, as many drivers will claim to have none, and discussion is difficult, as most do not speak English.
In Old Delhi and other neighborhoods you can still hire a cycle-rickshaw. It's a great way to cruise Chandni Chowk, explore the maze of narrow lanes, and get from one sight to the next. A short one-way trip costs Rs. 30; work out a higher fare, up to Rs. 200, if you want to ride around for longer.