Stress happens: don't forget to breathe! No matter how much you plan, things will go wrong. Roll with the punches; don't plan what you don't have to. Don't limit yourself to guided tours. Allow for the unexpected. And when the unexpected confronts you and things feel out of control, feel your pulse, if it's pounding (and you aren't running), then breathe deep! And again! And again.... The world's been spinning a very long time, it'll be fine, so will you, just breathe. Often the most stressful experiences become your favorite stories to tell later. They will also probably be the experiences that teach you the most about yourself and about how to maneuver in the world.
Get on the bus! Wherever you go, there will be a normal cheap method of transport. Often it is buses, sometimes its subways, trams, tuktuks, bodas, etc. Unless it's totally unsafe, (i.e. motorcycles without helmets, etc.) negotiate your fare and jump on. Not only will it save you money, but it'll give you a perspective on everyday local life and give you the chance to ask advice on what locals do. In turn you will meet interesting people, get ideas on unique things to do, and probably give you a taste of food off the beaten track.
Eat Local: In the years I've spent traveling; it's the local food that has always affixed itself to my memory. Your body will take time to adjust itself to the local micro flora, but that is true if you eat local or imported because it's different from your norm, so spend your time and eat local! And don't let looks fool you, just because it looks disgusting doesn't mean that it isn't the tastiest thing you'll ever have. Avoid seafood until you know it's good, but if it's well-cooked then it's worth trying.
Safety first: Your instincts even in a foreign environment are worth listening to. The general rules of "don't go out after dark without a plan, friends, and knowing what to do in an emergency" still apply, but more than that, listen to your gut. If you aren't sure, ask multiple (unrelated) locals, and then listen to what your instincts tell you.
If you end up in a tight space, never fight back, always give stuff up, back down and walk away. You won't believe me until later, but everything you owned (including your pride) for any length of time has sentimental value, so you (and I) believe everything we have is worth more than it is. That doesn't mean you should fight for it and I'll say it again, you should only take stuff you can replace on a trip. You will likely lose things and it's possible things will get stolen, it's also part of the experience, but your stuff doesn't matter as much as you do.
Rosie Cornick : The Leap: "If you decide to travel with one or more people then my main piece of advice is to make sure that you choose your travel partners very carefully. It is a hugely testing experience travelling with other people. You will be in a far more intensive environment than you probably ever have been before. Make sure that you keep lines of communication open with each other so things that may be bothering you get raised and sorted and won't fester turning into friendship-ruining issues. It's also important to adapt and compromise to each other. If you know that your friend takes half an hour longer than you to sort themselves out in the morning then make sure you set the alarm half an hour earlier if you need to be somewhere. The best way to ensure you all having as good a time as possible is to balance the give and take!"
Ross Fraser : Backpacking Holidays: "If you about to start University or are already there, working hard with the aim of completing your degree and joining the rat race, one thing you should do is go away travelling out-of term time, you will regret not doing it!"
"However there are lots to think about before you plan anything so here are my tips (from my own personal trips) for a happy backpacking experience from my own personal experience on the road."