Here are the essentials for getting your travel documents together before going to India:

Difficulty: Easy
Time Required: 1 day in person or 10 days by mail

How to prepare your passport:
Visitors to India require a passport that is valid for at least six months from the date of visa application with at least 2 blank pages available within the passport.

How to get an India visa
In person: India Visas can be obtained in person at the Indian Embassy or Consulate General in your area.
By mail: If visiting the Embassy or Consulate is not possible, applications can be submitted by mail or through travel and visa agencies managing the visa process for a fee.
Photos: Remember that 2 recent passport sized photographs with a forward pose against a light background are also required as part of the application.

How long it will take
In person: Same day. Applications are usually accepted in person from 9:00 a.m. to 12:30 p.m. and are returned usually from 3:00 p.m. to 5:00 p.m. the same day but individual Embassy and Consulate timings may vary slightly.
By mail: Applications by mail may take up to 10 business days to process after receipt of your application.

Duration and Cost
Validity: Tourist visas are usually valid for 6 months from the date of issue.
Cost: Check out with your Embassy or Consulate for the Fee..

Airlines
Foreign Airlines: Foreign carriers (which are generally cheper than their US counterparts) linking the US with India include Air India, Kuwait Airways, Emirates, and Aerosvit (Ukraine).
Major Airports Handling International Flights
New Delhi, Mumbai, and Bangalore are the 3 major hub cities for air traffic .

Customs
Indian customs authorities enforce strict regulations concerning temporary importation into or export from India of items such as firearms, antiquities, electronic equipment, currency, ivory, gold objects, and other prohibited materials.

Tips:
If applying in person, it's better to arrive early as invariably there is a line formed outside the building prior to the opening of the Embassy or Consulate.
Similar to other government agencies, if you do not have all your required documents for submission in the morning, you'll be asked to come the next day.

What You Need:
Your valid passport
2 recent passport photos
Cash or certified instrument in the fee amountt