It’s not that bad. The power, however, goes out all the time, all over India.
Judicious use of the Shatabdi Express will let you make a day trip of it. Take the morning train to Agra and an evening train back to Delhi. Book both before you leave. The trip each way is about 2 hours. The Shatabdi Express is nice because a meal is included in the fare.
Delhi has a metro system. It’s cheap, fast, and crowded.
Just as you would be suspicious of anyone spontaneously approaching you in public in the West, you should also be so in India. It happens a lot, and it’s not uncommon for a tout to try to guilt you into having a conversation that will quite likely lead to them trying to involve you in some scam.
In New Delhi, there are very aggressive (they will even grab your arm to lead you away) touts that hang out around the New Dehli railway station that will try to convince you that you need to go to the “tourist station” across the street, often by telling you that you need to confirm your ticket. Should you fall for it, you will be told that your ticket is invalid and pressured to buy a fake ticket. Under no circumstances should you follow any tout, regardless of where you are.
Book any rail tickets in far in advance as possible. The New Delhi railway station has a tourist booking office (a real one). It’s on the second floor of the railway station. Again, touts will hang out around the staircase and try to lead you to the fake office across the street. There, you will be able to get in the reserved tourist quotas. You will probably be able to get on a Shatabdi Express train with one, maybe two days advance purchase, though. Because you are traveling in the tourism off-season, you will have better luck with prices and availability.
Get a travel book. I used the Rough Guide to India, but after I got back I looked at the Lonely Planet and probably would have preferred it. If you go to the Rough Guides website (http://www.roughguides.com), you can read the introductory chapters.
You will get ripped off. There is no way to avoid it. Remember, though, that even a near-doubling in price for, say, a rickshaw ride, may only mean a difference of one dollar.
Don’t give anything to child beggars. “Did you bring enough for everybody?” applies here. You will not have enough candy for every kid in New Delhi.