Of course, the first and best bit of advice is not to refer to the British as "imperialist overlords." It's OK to refer to the English that way to the Scots, Welsh or non-Unionist Irish. But be careful about it, as you can never be totally sure, except during a football match, of a British individual's sense of ethnic identity.
For other advice, however, from now on we will gladly refer inquiries to Tim Dowling, American expatriate columnist for the Guardian. Today he offers an impressive array of great tips for American travelers in Britain. We offer an appetizing quotation:
Don't bring along any articles about British food clipped from the travel section of your local newspaper. The information therein does not apply. People rarely eat any of those foods with quaint names - Plum Duff, Spotted Dick, etc - commonly associated with Britain. They are being laid on for your benefit, or rather as a sort of prank.