Why so down on China? I found it wild - like Russia, but without the fear of getting kidnapped or shaken-down by the cops.

As for advice...

Don't plan too much in advance. Know where you're going to start and where you're going to end, but be flexible about what you do in the meantime. Some of the best experiences I've had have come from meeting people and hearing lines that start with "So I went to..." and "I've got a free seat in a car tomorrow going to...".

Be positive. When faced with a decision, don't think of reasons you shouldn't deviate from your earlier decision; instead, think of reasons why you should. You're from a prosperous country with a good passport, you speak English, and you've got access to someone at home with some back-up money to bail you out if you get into something really serious.

Trust your gut. Despite being in places you've never been and dealing with cultures you didn't even know existed, your sixth-sense of danger is still pretty good. Ignore the "this is kinda unfamiliar/scary" gut feeling, as that's the whole point of travel. But when you get the "he's gonna kidnap me" one, listen to it hard.

Dress up. Few other places in the world wear t-shirts and sneakers as proper attire for going out. Go to Old Navy (or somewhere else suitably cheap) and buy four or five solid-color polo shirts - these should be your go-to everyday wear shirts. Bring a t-shirt, but only for outdoorsy things. Also no cargo shorts. My standard attire for rolling into a country I didn't know was a polo shirt, some worn-in darker khakis, and a pair of Pumas. This will be appropriate dress (within one standard deviation) pretty much anywhere in the world. After you arrive, look at what everybody else is wearing and correct up and down. Especially in not-Western Europe, local clothes are dirt cheap.

Travel light. Pack your back as perfectly as you would like, and then force yourself to take out five or six things. If you need it desperately, you can probably buy it there. If you buy something there, you can probably ship it back.

Learn fix or six words of the local language. I can greet people, order and direct a taxi, and find the washroom in more languages that I can count. I can almost never understand the responses I get to those statements, but you can usually get the gist from the body language.

Don't let pictures get in the way of the real thing. If you're going somewhere to see a particular thing, look at it. Take photos as an afterthought - not the other way around, and may people do subconsciously. While you're at it, take an hour before you leave to get a hang of using your pocket digital camera without looking at it; I can hold mine in my palm, hit the shutter with my thumb, and have a pretty good idea of what the picture will look at - I make up for the "pretty good" part by simply taking lots of pictures. You can get photos of a lot more cool things when people don't notice the camera. If you can, get a camera that takes AA batteries, as well as the standard rechargeable - I have yet to go anywhere that doesn't have AAs at some price.

Get interested in sports. Know a few players who play for the Yankees, Red Sox, Liverpool FC, Manchester United, Chelsea, McLaren Mercedes, and Brawn Racing, and one or two reasons why you "like" that particular team. Armed with this information, you can strike up a conversation with a guy pretty much anywhere in the world. Probably a hockey team too, for the Canadian part of your trip. Also know that if you say "football", no one else will think you mean the kind in which you score a touchdown.

Do some reading. Not guidebook, but literature - both fiction and non-fiction. If I know I'm going somewhere, I'll try and find a few books written by authors from where I'm going and/or about where I'm going (ideally both). It gets me excited about the trip, provides some local background, and gives you a few common cultural reference points before you even get there. Your local independent book store is key for this - if you can find one that specializes in travel literature, even better. The best one I've found so far is in London, and they organize their travel section by country, as opposed to by topic. So if I was going to Argentina, I'd go to that section, and it would have guidebooks, cook books of Argentine food, books written by Argentinians, and books written by others about Argentina. Many countries have one "classic" or "definitive" book about them; see if you can find them (e.g. Argentina's is Bruce Chatwin's In Patagonia).

[Note that most of this advice is about the non-Canada/US part of your trip. Canada is very similar to the NE US except with different accents/slang/minorities, and fewer guns.]

Lastly...

Ignore this advice, and all the rest you get here. Travel is really an organized series of mistakes. Some end well, some don't, some you can't really tell. Accept what happens, go with the flow, and try not to die. Do that, and things will work out fine.