By far the most common complaint reported by first-time visitors to India is fatigue - simply trying to do too much in too little time. India is vast, colourful, and addictive, but have realistic expectations about how much you can see. A wisely planned visit to a particular area can deliver far more of the unique texture and spirit of the place. And remember, India isn't going anywhere - you can return time and time again.
Though perhaps a clichè, the only way to get a true sense of India is to visit smaller villages. The real benefit is that it'll get you out of the sprawling and vastly populated cities. Once you've cleared your head, say with a trip to the mountains or into slower-moving land of Kerala in the south, you'll be far better placed to enjoy the famous hospitatlity of the Indian urbanites.
A dodgy stomach is pretty common for first-timers in India. That doesn't mean you should rule out street food, but try to stick to peeled fresh fruit and foods that have been either boiled or fried. Stay on bottled water and avoid salads and ice.
This isn't really a popular concept in India. You will be squished on public transport and squashed in lifts. People will ask seemingly intrusive personal questions that you may find intimidating. Remember that this is a wholly different culture and the questions are merely indicative of the local's polite interest in you.
Be aware that India has a relatively modest culture. Covering arms and legs is a simple step toward respecting this. Indians are forgiving of those who aren't familiar with their culture, but you can quickly make a good impression by, for instance, removing your shoes before entering someone's home. This is particularly important when entering a sacred space, like a temple. Also, if you see shoes outside a shop, it's a sign to remove your own.
Feet are considered to be unclean in India, so if you touch something with your feet it's appropriate to swiftly apologize. Similarly, eating or passing objects with your left hand is considered unpleasant for reasons best left to the imagination. If unsure of local customs, keep an eye out for what others do and imitate.
You may well find yourself waiting half an hour in India when your friend has assured you they will be five minutes. Traffic and other interruptions can also mean that getting around can take a lot longer than expected. Build in plenty of room for unexpected waits and make sure to check opening hours - many government offices and shops close in the afternoon for lunch.
While "don't go down dark streets alone" might seem a bit obvious, there a plenty of straightforward ways to avoid subtle dangers in India. Carrying huge quantities of cash isn't a good idea anywhere, but in crowded Indian cities pickpocketing is a very present problem. Equally, haggling at a market can, at times, become unpleasant, heated exchange. Inexperienced visitors are advised to try to stay cool. Be pleasant but firm, and don't allow yourself to be irritated.