I have tried to build the most important tips into the rest of the guide, especially in the sections: RTW Packing List, Planning & Preparation, Health, Email, Contacts, and Companions. These are some tips that couldn't fit in the rest of the guide, or I would like to emphasize.
I would like to stress one thing before you go: you can never drink too much water. Saving money on water is no savings -- you will know what I mean if you ever have a kidney stone. Worse, dehydration can lead to a pancreas infection. You have a built-in dehydration indicator: the color of your urine. If you are dehydrated and drink a liter or two of water, you will notice it clear up within a few hours. Don't wait until you are thirsty. Drinks containing caffeine (coffee, tea, soft drinks), alcohol, and high levels of sugar (soft drinks) are not good replacement fluids because they are diuretics, which cause even more fluid loss.
Always carry food and water on buses and trains. Besides the usual delays, there are places where the food along the way doesn't look so appetizing. Also, especially if you are alone, you might not want to lose your seat, nor risk your transportation leaving without you, or with your bags still on the roof!
The key to staying on schedule is getting up early and going to bed early. The majority of transport starts out in the morning to get there faster. This also allows you to arrive early and find a good hotel room, and leave enough time to see more of a place.
In tropical environments, go to bed early like the locals, and get up early to see the most fascinating event: everyone starting their day at sunrise. A side-benefit is that you will experience more of the culture you came to see, instead of staying up late partying with the tourists.
Once every week or two, eat at at more expensive restaurants to get an appreciation of how good a country's cuisine can really be. The street food is basically cheap fast food that anyone can cook, and tends to taste the same.
If you bring good clothing, do your own laundry, otherwise your clothes will: turn strange colors, not always get so clean, and not last very long. I had many shirts and pants scrubbed or beaten to death, especially around the collar!
You will make many friends while travelling, and will probably also visit them when you get to their country. Likewise they will probably want to visit you. When you are given addresses, write them down in your book, then send the original pieces of paper home by airmail every month or two. I have seen many people lose their addressbooks, making it impossible to visit or contact any of the people they had met.
If there are things you are interested in, or become interested in, start collecting them early. This doesn't mean just buying things. I wish I had photographed many things, especially the huts in rice patties, and sketched the way they were built. I also wish I had spent more time watching people cook things, like the many varieties of banana pancakes that I cannot seem to replicate.
Some tried-and-true ways to prevent or minimize burnout: Travel slow and with a purpose. Stop every now and then. Learn the language. Avoid Western tourists a majority of the time. Don't drink alcohol. Go to bed early, get up early, and guard your health. Don't live too cheaply. Have people to visit. Don't have a family that guilt-trips you over family obligations!
The Bathroom Diaries
Swimmer's Guide to Pools Anywhere in the World