Unless carrying an Indian, Nepalese, or Bhutanese passport, should apply for a tourist visa from their nearest Indian Consulate or High Commission. This is valid for multiple entries for a prestipulated period of time from the date of issue (this will depend on your travel dates and the country in which you are applying). Given the nature of India's bureaucracy, the rules and fees for application change regularly, so it's best to check with your travel agent or with the relevant authority for the latest visa information. Accurately completed visa application forms must be accompanied by two passport-size photographs (on a light background) and the appropriate processing fee; apply well in advance to avoid unforeseeable delays. You won't be admitted to India unless your passport is valid for at least 6 months after your entry, and it should typically also be valid for at least 3 months beyond the period of your intended stay. Check for fee structure and more details at www.indianembassy.org, but note that a number of Indian embassies and consulates now outsource the visa procurement process, meaning that you need to go through a third-party that specializes in dealing with entry visas.
If you're applying for a visa in a country where India does not have a representative, you are advised to make inquiries at the nearest British authority.
A special permit is required for foreigners wishing to visit the Lakshadweep Islands, as well as sensitive border areas including Sikkim, parts of Ladakh, and certain roads in eastern Himachal Pradesh. For Lakshadweep, your permit will be arranged when your accommodations are reserved. Permits for the other restricted regions can be obtained in India, sometimes within a few frustrating hours. Carry a number of passport-size photographs and copies of the personal particulars and Indian visa pages of your passport to apply for these permits.
What You Can Bring into India
You can bring as much foreign currency into India as you like; if you have over $10,000 in cash or traveler's checks, however, you should complete a declaration form. You may not import Indian currency into India. In addition to your personal effects, you are allowed 2 liters of alcohol, and 200 cigarettes or 50 cigars. (Know that foreign liquors and imported cigarettes are very heavily taxed and in some areas difficult to come by.) You may carry a cellphone, camera, and pair of binoculars, but officially you may have only five rolls of film. You must complete a special Tourist Baggage Re-Export Form if you are carrying valuables such as a laptop computer, major video equipment, special camera gear, or high-value jewelry. Although there is a strong possibility that you may encounter difficulties upon leaving if these forms are not completed, you'll discover a general malaise among Customs officials, who seldom hassle foreign visitors on international flights. Also, much of the bureaucratic heavy-handedness has eased in recent years, and there is less suspicion of foreign travelers. In fact, arrival in India is incredibly straightforward and generally hassle-free.
What You Can Take Home from India
You may not export Indian currency. Exchange all notes at the airport before you depart. Note that airport money-changers frequently run out of certain currencies, so you might want to complete any exchange before you go to the airport. There is a restriction on the exportation of anything over 100 years old, particularly works of art and items of cultural significance. It is illegal to export animal or snake skins, ivory, shatoosh wool, or anything that has been produced using these materials. Generally, jewelry valued under Rs 10,000 may be exported, while gold jewelry valued up to Rs 2,000 is allowed.