A multidimensional metropolis
Delhi has a reputation of being an unsafe city after dark, so it is advisable not to venture out alone in desolate places. Women travelers are especially cautioned to try and avoid traveling around on their own. Two is always better than one, and will not invite unwanted behavior.
But again, after dark, women should try and move around with a fellow male. While sightseeing in crowded places keep your wits about you at all times and pay special attention to your belongings. Do not, for any reason, leave them unattended or with a stranger. Do not lend your camera/camcorder to anyone.
If you are traveling by bus, try as much as possible to avoid very crowded buses. Incidences of pick-pocketing and harassment of women are high in such situations and are therefore best avoided.