When you're looking at a map, it's hard to gauge the sheer size of India. It's big, really big! To give you an idea, we took a direct train from Goa to Rajasthan, a journey that crossed about a third of the country, and it took 27hrs. When we went from Kathmandu to Mumbai it took us the best part of 5 days of overland travel. Like I said, it's big! Fortunately India has a fantastic transport network to ferry their 1.2 billion residents all over the country at great prices. Here's a guide to help you get around without losing your mind.
Byfar your best bet for covering long distances around India. When you book your train there are four different classes, there's 1st Class but don't even think about it! Even 1st Class in India is retardedly expensive, it would actually be a lot cheaper to fly. It's basically for the Uber rich who like to show off how much money they can waste.
Then there's 2AC, this is the next step down and is a fraction of the cost of a 1st class ticket. It's generally a lot quieter, you get curtains to section off your area of six bunks and you even get a blanket, which you'll need it cos it gets bloody cold! The down side to 2AC is that all the windows and doors are kept shut, so if you smoke, you can't! This is also the class most foreigners use.
Next step down is Sleeper Class. This is the one we would always book. We always felt like a snob taking 2AC, and besides sleeper is about half the price again. Sleeper also comes with bunks, stacked three high with big fans on the ceiling. When it comes to booking your bed, make sure you get a top bunk, even for a day journey that you're not planning on sleeping on. The middle bunk is folded down during the day (from about 6am until about 10pm) and the bottom two bunks become seating areas and they can get rammed full of people to the point they are standing in the middle and you wont get a minutes rest. At the very least you'll be stared at by about 10 people for the entire day. (Never challenge an indian to a staring contest, you won't stand a chance) Also, if you get up to go to the toilet, you probably won't have a seat to come back to. The top bunk is always down and you are above everything giving you your own little sanctuary from the masses. If we couldn't get a top bunk for when you wanted we would wait for a few days. Trust me; ALWAYS top bunks!
The other option is General Class, costs virtually nothing but even if you're lucky enough to get a seat, you'll probably have someone sleeping on your feet and someone sleeping in a hammock hung from the luggage racks above you. There doesn't seem to be a maximum capacity for these carriage and it sure as hell doesn't look like a fun time. You're best off paying double the nothing and going Sleeper.
A few drinks before you take the train will definitely make the trip less painful, but be careful if you take it on board, it's illegal to do drink alcohol. Also make sure you have a collection of small notes (100Rs or less) with you for the journey because there's basically a walk on market at every stop! Chai, birianni, samosas, water, coke, all sorts of food and drink, even things like nail polish and hair ties get paraded down the aisle and its all super cheap. And don't worry about sleeping through it, they make sure everybody knows what they're selling as they walk through.
"Chai... Chai... Chai...", "Biriyani... Biriyani... Biriyani...", "Samosa... Samosa... Samosa...". All fucking night.
Slightly more comfortable with a lot more privacy are the sleeper buses. Buses with bunks basically. They cost a bit more than trains, but you get a sectioned off double or single bed. Now I say double, by that I mean there's enough space for two normal sized Indians to sleep side by side, its a large single basically. It's fine if you're travelling with a partner or mate, but if you are by yourself, make sure you book a single! If that's not available, pay for two people or wait it out. They will put a random person in there with you to share your 'double' bed. A mate learnt this the hard way who had an 11hr trip sharing with a random Indian guy who was filthy and stank. Buddy woke up face to face with him at one point in the night to find his new friend not only sharing his pillow, but dribbling on it too. Yeah, it's worth waiting it out.
Now the biggest problem with the sleeper bus I'd that they only stop about once every eight hours, so if you have a child's bladder, like Carly, you could have problems. She has to watch her liquid intake for the entire day. Alcohol is definitely a no no before an overnight bus. That and Indian roads are the last place you want be at night (see Scooters below)
Back on the plus side, if you take the non AC option, you have your own window which opens. Which means you can have a smoke.
India has a ton of budget airlines (Spice Jet, Indigo, GoAir to name a few) with a pretty extensive route network around India with flights usually costing between $30 and $70 (£20-£50). No doubt you'll fly to India on an Indian airline, well that flight is going to set the standard for any internal flights you might take. It's mind boggling watching Indians on a plane, they literally don't listen to anything the cabin crew say and there always seems to be someone walking down the aisle as your landing.
However, as easy as taking a flight is, it's a cop out! Part of the Indian experience is travelling the country like an Indian using trains and buses.
Now the best way to get around an area you're staying at is by scooter or motorbike. In most places where there's some form of tourist attraction, there will be somewhere to rent bikes from for a few hundred rupees a day. Do it! Even if you haven't ridden one before, you'll be fine. As long as you can ride a push bike that is. Its great fun ripping out into the desert or down coconut tree lined roads.
Make sure your bike has a horn though. This is more important than mirrors and as important as a helmet! In India your horn is your armor, every time you overtake, horn. Every person walking on the street you pass, horn. Basically, if anyone or anything is near you, horn. Mirrors here are for making sure your moustache is straight, not for checking behind you. Both drivers and pedestrians will change direction right in front of you and cut you up if you haven't horned. If you hit someone from behind, it's your fault even though the bell end you hit didn't signal or look before cutting across the lane.
Fuel stations can be found here and there, not as often as in the west though. Chances are at some point you will run out of gas due to the fact that you only have a 5% chance of having a working speedo and fuel gauge. Fortunately pretty much every road side store will have plastic bottles full of petrol on the roadside (generally left baking in direct sunlight all day) for sale at about 20p a litre more than a gas station so you won't have far to push because these shops are no more than a few hundred feet apart in most places.
Renting a scooter is great fun but Indian roads are pretty dangerous. People overtake on blind bends, drive on which ever side they fancy that day and on coming cars have no problem with overtaking and pulling out right in front if you. General rule of thumb is that the bigger you are, the more right of way you have. Oh, and Indians have literally no idea about the difference between high Beam and low beam, they just drive around with their headlights on full, blinding everyone driving the opposite way.
Scariest of all though is the drink driving. We've seen first hand, taxi drivers going into a local off license, buying a 150ml bottle of rum, pour half into a glass, neck it, drink some water then smash the rest and proceed to get back into their cab and drive off. This happened several times. Apparently truck drivers are also really bad for it as they driven through the night, which is believable when you see the number of trucks on their sides or flat up against a wall.