Footloose in Old Delhi
The tour will help understand the rich culture, diversity, architecture, food and the choas all in one. It throws open some of the best and worst things one can imagine. The breathtaking beauty of the grand structures and the filth around would present things in stark contrast to each other.
The trip is best done on any day except Sunday, as many shops are closed then. A walk on Sunday would present less humdrum and activities around the place. Saturdays, on the other hand, tend to be particularly busy.
Bring a bottle of water and your camera, but leave any other valuables at home — the Old City is crowded and there are pickpockets lurking about. It is preferable to keep the camera hanging in neck or hold it in hand as generally if kept in pockets, it can easily be pick-pocketed.
 Get in
The starting point of the tour is Chawri Bazaar station on Delhi Metro Line 2 (Yellow), and the endpoint is Chandni Chowk, the next station on the line.
The Chawri Bazaar station has two unconnected exits, so take the north one to Chawri Bazaar, not the south one towards Ajmeri Gate.
As you clamber to the surface, you'll find yourself in the middle of a bustling bazaar — this is Chawri Bazaar. Hail a cycle rickshaw and ask him to take you to Jama Masjid, which shouldn't cost more than 20 rupees (word of advice - choose one without sunshade if weather allows as it provides better view and might be less expensive). It's not far in terms of distance, but it'll take a while, as the bazaar here is always packed to the hilt, but this just gives you a good chance to look around. Many shops on Chawri Bazaar and adjoining Nai Sarak are devoted to stationery, and in particular the colorful, handmade and exquisite invitation cards that are a prerequisite for any Indian wedding.
Soon you'll see the great dome of Jama Masjid, India's largest mosque, looming ahead. The cycle rickshaw will drop you off at one of the gates, so take off your shoes and head in. Entry is free, but a photo permit is Rs.200 (a note on photo permit - if you carry a backpack - they'll assume you have a camera. Even if you don't plan on taking pictures - if you have camera on you - it will be Rs.200. Interesting thought is to give your camera to your companion and get charged for only one). If you donot want to pay for the camera, give it to your companion and go empty hand. They would then ask if you have a mobile phone with camera and if yes, they will ask for 200 again. Even if you have nothing with you, they may still ask for 200 and in such a case you have to show them the rules written near the gate which says that 200 is chargeable only if you have camera. DO wear some dress which is not at all revealing and covers all your body including legs and it would be easier to get into the mosque. The gatekeeper will want a little baksheesh if he keeps your shoes for you (carry a plastic bag if you like to keep your shoes with you). The gatekeeper may be very rude and may try to manhandle you. Argue with him without being aggressive. Climb to the minaret (an extra Rs.100) is overrated - the views of the city are great but metal grill all but prevents any kind of decent photographs from being taken plus top has very little room so it gets very crowded very fast. Also your feet/socks will get really dirty on your way to minaret. Word of caution about restroom - they expect you to pay something for it (Rs 1-5 seems to be ok) and then to squat to do anything - no standing up for men - very awkward.
Consider hiring a local guide to take you through Old Delhi's streets and to show you old haveli (houses). One may be available near the mosque gates - but bargain hard - asking price may be as high as Rs.550/hr (completely insane) - something along the line of Rs.150-200/tour is still on the high side but probably reasonable.
* To add: Karim's http://www.karimhoteldelhi.com/
Karims - a very famous and old local eatery - is in a bylane called Gali Kababchi, which is on the daryaganj side of the Jama Masjid - just few steps away from the mosque. The health conscious should stick to the roasts and the tandoori items and eschew the rich fare of the kormas and stews. Avoid second floor which can get very warm. The place gets full very quickly - so consider timing your visit to off-lunch/dinner hours.
Eastward from Jama Masjid, you'll see Meena Bazar, a popular flea market with antiques (and not-so-antiques) — it's also known as Chor Bazar or "Thieves' Market," so hold onto your wallet and don't believe every claim you hear.
Head out from the mosque's north gate and follow the curving road, then turn left. Many shops here specialize in fireworks, another Indian wedding staple, but right up the road is Cycle Market, which deals not just in bicycles, but in cameras.
You've now reached Chandni Chowk, the central street of the area. It was built by Shah Jahan, the builder of the Taj Mahal, as a tree-lined, half-moon shaped promenade (hence the name, "Moon Market"), but little but the name remains. To the east is Sri Digambar Jain Lal Mandir, a major Jain temple, and behind it is the Lahore Gate entrance to the Red Fort (Lal Qila), but that's worth half a day in itself and best left for another day.
 Stay safe
Old Delhi is full of pickpockets, so don't take any more than you need and keep an eye on your cameras and bags. Though the chances of losing things is high, those of finding them are too, on the same day if luck favors. This is because most of the stolen articles reach the Chor Bazaar, or Thieves Market, where you can buy your own articles back rather cheaply!
 Get out
Take Chandni Chowk' metro station or backtrack to Chawri Bazaar station on Delhi Metro Line 2, also know popularly as Yellow Line. Hiring rickshaw is always a good option to save walking - just negotiate your rate. However, during weekdays it may be wise to take a walk in view of the narrow roads and the flow of humanity.