Well, for one thing, don't expect "abroad" to be one big thing. You can expect different things travelling to Japan than you can from travelling to Botswana
I'm sure you know, I'm just making fun of you here.
Anyway, in Japan, you can expect most young people to understand a bit of English...But certainly not all of them, and certainly not a huge percentage of older people. Though it also depends where in Japan you're going - big differences between cities and more touristy places vs more rural places.
Try to learn at LEAST the basic 5 or 6 phrases (thank you, sorry, hello, good bye,...) in a native language. You may think "sorry" is the same worldwide but I know people who wouldn't understand the word. Being able to apologize is important (in the "sorry, I don't speak you language" or "sorry, I didn't know this was bad/wrong/illegal/improper/against etiquette/abnormal here" way). It'll also get you a lot of leeway and respect in most places; trying is often enough to get "locals" to warm to you.
Be aware of local customs. Don't expect them to be the same "all over" - what's normal in Tokyo might not be in Kyoto. The USA is a
huge country and culturally fairly homogeneous - even so, I think you can understand you'd behave/dress differently in New York than you would in southern Alabama. Such differences in opinion can be found much clsoer together than that as well, certainly outside the USA.
Don't act arrogant or expect other people to know what you mean/want/intent. It may seem blindingly obvious to you, but not to them - some people aren't used to foreigners, and even the most clear and obvious things may be completely weird and foreign to them. As a silly but, I think, telling example, there are a few cultures (not in Japan though
) where an "arrow" is actually interpreted the other way around. "-> " would be considered "look left" - since it's seen as an open eye, looking to the left, instead of a line "pointing" towards the right.
Anything could be weird or different. You're tall, pink, and red haired. Expect to be stared at if you end up in places where westerners aren't common. I've been in places in Africa where we were amongst the first white people they ever saw. Children were groping our hair because it was straight instead of curly etc. Very movielike and shit. Our skin didn't really faze them or surprise them, but our hair! Heh.
Anyway, try not to be too much of the stereotypical tourist. Also, try to not mind being taken advantage of (a bit). Especially poor people abroad tend to think Western people are "rich". Even though we aren't, we often are, comparatively. Not really applicable to Japan, I guess, but sometimes, it's not worth haggling or protesting...paying 10 cents more for some tidbit doesn't harm you, and it may mean the difference between food or no food for someone elsewhere. On the other hand, don't let them get away with clear rip-offs, and do'nt be afraid to just get up and go elsewhere if you have the feeling you're in danger or being taken advantage of. Especially as a woman, sadly.