The other side of the coin, based on 10ish days in country, observing the natives.
un: have a happy, positive outlook! Why not? Chin up, head high, hair back, embracing the world! No more hunched shoulders apologizing for existing! No more mumbling! Laugh loudly, don't chuckle! Use exclamation points!
ail: chat more. with people on the street, with waitstaff, with your drycleaner. show your interest in other people by connecting with them verbally. Without introduction.
In REI, from behind, while I'm trying to find a non-materno-fashion shirt: "Love your bag" [me: beat, hestitate, was she talking to me? oh. um...] Thanks! [proceed to chitchat about backpacks, single v. double shoulder, aging computer bags, and then get recommendation on fab running socks that I must have. I buy them. Because we talked, obviously.]
Note to British people trying this out: you have to practice the chat. It takes some doing to generate streams of verbal exchanges that are *not* about the weather. I find commerce facilitates such practice and chatter. Americans connect via the shopping. It's all very friendly.
tre: two words: iced tea. I know I know--it's too cold in Britain for this sort of thing. And sure, tea in its Platonic form is obviously hot, preferably black with cream/milk, and served whenever anyone arrives at your house. These things are all true. But there's something about iced tea that we can separate from tea-ness and put in a different category of icy goodness on a hot day. Of course, you'll need to wait until there is a hot day, and also work out how to do ice trays in drawer-based freezers, so there are infrastructure issues. But still. Iced tea. Genius.