if you are not aware much of delhi places, people and culture/trend and are totally new to the city, the main concern for me will be safety, be it any city.
traveling:
Priority - Night Travelling / First Time - Branded Cabs
please ensure you have the decent and branded cab services if you are hitting moon after the party and want to go home or are too late in night. Few are: 011-41414141 (Mega Cabs), 011-42424242, 011-44224422. Always keep a card with your residential address in it. Although drivers in delhi are smart and understand, but sometimes accent can be a problem, so keep it!
These days, the prices is like INR 20 start and then INR 20 per kilometer and INR 50 for waiting at one place for 30 mins. This is currently the price of the reputed cab providers. all have a/c , comfort and clean seating.
Priority 2 - Day to Day - Auto Rickshaws if by road
For day to day travel / commuting, an auto-rickshaw will be better deal but remember you go by meter. But unfortunately, 80% are not have there meter running and will ask for fixed price. Seeing a foreigner, it might be like double the price. Negotiate well and negotiate like INR 7 per km.
I am enclosing the govt rates for the taxis and rickshaws from Delhi government police website for yoru reference. They are a bit cheap (INR 11 for non-ac and INR 13 for ac) and is not available at all places but in common public service places like Stations etc. URL -
Priority 2 - Day to Day - Metros
For day to day travel / commuting, nothing beats metro (DMRC). It is a shuttle service that has a good linkages in delhi and cheap. At office timing, it can be a bit too much, but then it is A/C, fast and cheap! Females have a seperate compartment but busy timing or high traffic, we can see few men standing in corners of the compartments. It runs from 6 in the morning till 11 in the night. For more: - delhimetrorail.com/
[b]Priority 3 - Cheap Travelling- Buses
Avoid travelling in private buses and public buses only if you see Red Color DTC (Govt buses) which are AC and decent.
Travelling cost can range from INR 5 to INR 75
Walking :
Mind it, most of the delhi areas are clean in the morning but then it is mostly occupied by vendors etc. So, for walking, be ready to use road sides to walk. please ensure you look left n right before crossing roads, even if it greeen light for pedestrian. also, people coming from opposite side don't hit you !
Carrying Valuables while travelling :
Please keep your wallet in your pockets (front) and keep change for travelling in other pocket. A very useful tip that has helped me (being a delhiite) when my back pocket got picked and what all he got was a cheap wallet and 100+ INR
. Keep road map and and official document in your bag strapped tightly!
Don't take lifts from unknown, tell them politely, i am walking as i have to go to that place (pointing your finger at any building nearby) and tell them all your friends are there. 
dont eat anything they offer (even if they mention it is sacred and deity etc). Ask them your doctor has asked not to have anything for next 8 hrs
simple!
dont leave your luggage unattended for a minute. you might only be left with memories.
dont try to carry your mobiles and laptops and other valuables flashing to the public. use it sensibly and keep it in your hands only.
dont argue and dont get provoked! some might be rude but yu do not need to be!
For more guidelines for foreigners in Delhi, Delhi Police has mentioned few details that may help you.
Delhiites are smart, educated ,respect foreigners .. but the above tips are few pranksters who try to break the beauty of Delhi by doing non-sense. the above are just few ways you can avoid being in trouble while travelling!
i think today's holiday i have utilized enuf
!