It always hurts me when I have to take measures to keep myself safe, in my country of birth, India. Despite all the sadness, anger and frustration, I share the spirit and enthusiasm of women who live in India & who want to visit India. Deep down I know and understand what this land and culture offers to help us grow as a human being and I believe its worth cherishing & exploring. When you're required to take measures for your safety & comfort, here's my take on the little and not so little things to do.
I have lived in all the metros of India and as a street photographer I have also traveled a lot within India. Talking about safety, the first think that comes to my mind is of-course clothing!!! I have seen lots of travelers posting their pictures in salwar suits, which is a common style of dressing for Women in India. In the picture below its me in a salwar suit, I strongly recommend you not to wear it while traveling. The salwar suit is the first option for a lot of women traveling in India because it covers your skin very well and you see many Indian girls wearing it very comfortably but they wear it mostly because of social taboos & compulsion, than by choice. I would never prefer a salwar suit if I'm not in my comfort zone, because if I were in any danger it is always tough to react in, tough to run & even tougher to kick some ass in. I would rather prefer wearing a regular denim, with some kind of a top which covers my butt, as this would sufficient to keep all the perverts away and will always keep you active. You can also consider wearing 3/4ths instead of wearing Jeans.
Taxi or no taxi, even if you have to wait for hours, look for an auto but never ever think of taking a bus unless you are in Bangalore, people and buses are nicer there but they charge you as much as an auto so its matter of preference and availability. In Delhi you find similar looking buses as Bangalore but its never a good decision to ride one of those.
When you travel in a train and you don't have any male friends with you, always travel in a three tier compartment, it depends on the route but you meet some of the biggest jerks on the planet in Indian trains sometimes. I have traveled in two tier compartments many times over many years, but this one time the compartment started to empty out on the route and some idiots around me, who were by the way idiots from the first moment, started behaving more senselessly. Well probably lowlifes like those, just cannot enjoy themselves if women aren't living in fear and are living the freedom that we claim by traveling alone.
I'm going to tell you about another one of my train experiences. Once I went to see off a friend at the New Delhi railway station and I witnessed complete craziness, a Caucasian lady found herself in a situation where she had bought a first class train ticket and she found herself in a seat surrounded by three misbehaving moronic men. Now she wanted to exchange it with somebody else so that she can travel safely. On the platform I could see that she was nervous & exhausted at explaining the whole situation to the relevant authorities & requesting them to change her berth. They were in the beginning trying to fake it with her that they didn't understand English, then they switched to saying that they couldn't do it lawfully. None of those excuses were true & when she persisted & didn't quit & finally when the train was about to leave the station, they had to do what she was asking. One of the biggest tools in India if you sense danger or deliberate discomfort and you think that a particular thing can help you feel safe, ask for it & make some noise letting the people around you know. Crowds always scare Indian men so gather a crowd & then they are bound to behave accordingly.
Seeing women around everywhere is rare in India, but never take this as a general indicator and hire a hotel in which you do not see women, it is always going to be a bad experience. When you are hiring a hotel look for a place with women travelers, I have stayed in everything from budget hotels to 5 star hotels, of-course star hotels do feel much safer and healthier, but our pockets don't always allow this, so it can be a little tough but never impossible to find a safe hotel within your budget. (The picture below is of me at the Taj hotel in Kumarakom, inside their enclosed property.) In northern India it is common to find local female dressed in saris but they're also enthusiast travelers :) but it is a rare sight in southern India. So your only hope in such a situation are international tourists, if that doesn't work out you'll have to pay a little extra for your safety. While I was traveling in Mysore, I paid 2000 INR per night for an below-average hotel which only had one more female traveler, an American girl. If you have Indian girlfriends staying at a paying guest (PG) accommodation, you can stay in their place with little money & some negotiation, those places almost always let you stay.