Within most of India, taxis are arguably the best mode of transportation. However, always ask for the price beforehand or insist that the driver uses the meter.
Local buses and trains also run often, however, the only problem may be spotting the one you need, as most of the information is written in the local language, which could be one of 22 official languages. Also, some of the popular routes may be very crowded. On the plus side, most Indians in the cities have a good grasp of the English language.