I'm going to try to help you.
Type of conversation people are typically receptive to:
*gentleman 1 is reading a book about English, gentleman 2 approaches and speaks in a normal tone of voice*
Gentleman 2: "Oh, hey. That's the coursebook for module 232, right?"
Gentleman 1: "Yeah."
Gentleman 2: "Where did you get it? It's so expensive from Waterstones."
Gentleman 1: "Yeah, I got it from Amazon instead. So, I guess you're on the same course?"
Gentleman 2: "Yeah. I'm Mark, by the way."
*conversation develops*
This conversation was successful because it was relevant to something that someone was doing at that moment. There was a point in beginning a conversation (the question about the book, whether from genuine interest or not) which then developed into further discussion.
Type of conversation people are not typically receptive to:
*gentleman 1 is reading a book about English, gentleman 2 approaches and speaks incredibly loudly from 2ft away*
Gentleman 2: "HEY, ARE YOU GOING TO THE GAME TONIGHT? IT'S SO KOOKY HERE. WOW, BACK IN OREGON WE HAVE THIS TEAM THAT I REALLY LIKE. YOU ENGLISH PEOPLE ARE SO QUAINT. WHY DO YOU GET IN A LINE FOR THE BUS? IN MERCA WE JUST GET ON IT."
Gentleman 1: "..."
This conversation was not succesful because gentleman 2 talked in the stereotypical LOUUUUUD American voice, which he may not be aware he's doing. He is not talking about anything relevant, there was no natural introduction into the conversation, he just started talking about anything.
So my big tip is to make some kind of relevant comment. Instead of going, "HI I'M ERICA" on the bus, people will be way more receptive to asking, "Hey, this bus is going to ___, right?" and then developing a conversation from that. You may not get on first name terms until a few minutes later, or not at all if you're just making small talk with someone you won't see again. It's all a game, my friends
which I think relates to this, somewhat:
You see it as being unfriendly, but what I think it really comes down to is that we're less direct, and you have to know the "rules" of conversation, as it were. Tricky business indeed. I'm sure some eventually pick it up and learn our mysterious ways.