First time in India is not the time to start "roughing it", give yourself a few days to adjust, and spare yourself the 24 hour unreserved train journey.
Transportation- the place where you get the most bang for your buck, splurge on the good buses/trains, it makes a world of difference in how you feel when you get off, and the price difference is usually not too much.
Trains- are really easy to book online. To figure out which train you want, and if there's availability go towww.indianrail.gov.in . Then to book your journey, go to www.irctc.co.in . Alternatively, go to one of the tourist reservation offices at a main train station (New Delhi is the best one). Now which class? for long journey splurge on AC (Chair car, 3AC, 2AC), that's the only way you will have an assigned seat/bed and no problems with it. Sleeper car is also ok for daytime trains, but not the best for sleeping, as all the cars are open to the outside and people constantly walk around. Remember, never accept food from strangers as there have been attempts of poisoning in order to steal your bags.
Flights- most internal destinations average around 100 USD.
Bargaining- it's part of traveling in India so bargain hard, all the time, especially in touristy places, try to ask locals what the price should be (for rickshaws, produce per kilo, etc).
Shopping- the best deals are to be had first thing in the morning, try to be the "first customer" and don't forget to bargain. Many goods will be cheaper in the Delhi Main Bazaar (Pahar Ganj) than they will in their state of origin because wholesale shops are located there.