I had incredible time in India but I followed a few guide lines so I had a better time in India,
Going in the right season is very important as during the monsoons season it will rain a lot and the roads will be flooded. This will be breeding ground for Mozzies as well, some months will be too hot as the heat can be unbearable.. All this can ruin your holiday.
The right months to go are in mid November, December January till mid February, the weather in these months is more suitable for us and it will make our trip to India so much more worthwhile. If you can look beyond the dirt, dust, poverty and traffic chaos then India is most Amazing, magical country and is definitely worth visiting. It is a great place to be as the people are warm and friendly.  
 I would suggest to stay in good hotels so you can have cleaner facilities and you can remain well on your holidays. You can be pampered at the nice hotels with massages and beauty treatments at a small price.  Also eat in only good restaurants as food is cheap in India and there will be better hygiene at this restaurants. 

I drank bottled water all the time. Make sure when you buy the water bottle that the lid is screwed on properly. 
I took all these items with me all the time in little backpack :)

* Wet wipes, 
* Anti bacterial gel, 
* Small pack of tissues,
* Small face towel ,
*Sunblock
* Deet - 50 % deet which I bought from Boots the chemist. To avoid being a Mozzie magnet take Vitamins B complex one month before the travel and throughout your stay in India as this is suppose to minimize the Mozzie bites.  
*Hat  & also umbrella  (For sun and rain)
*Emergency medication
* 2-3 plasters
*Comfortable shoes
*Bottle of water.
* Spare batteries for camera
*A small torch.
Some toilets might not be v clean so always keep small packs of tissues handy. 

Food
 
 Most Good hotels serve both Indian and Western Dishes, for breakfast you do get good selection of both cuisine with eggs to order. 
 I ate mainly in good restaurants and hotels most of the time, they do make sure to use filtered water to cook and wash vegetables/ fruits.
 But when I did eat at the little restaurants, I made sure that I ate only hot food and I avoided salads which might not be washed properly, Lassi as they might use tap water and I completely avoided eating cold food at these little places.
  As we were on the road a lot, we ate lot of Mangos and delicious fruits which we made sure were properly washed.
Also drink lot of coconut water as it has antibiotic qualities and is helpful for mosquitoes bites.
Be careful what you eat and you will really enjoy your time in Magical India just like I did ...