First and most important: forget the past.
Yes. You have seen England play well for a while and "dominate" teams (good and bad) for some quite lengthy periods. You have seen them look like a Modern Football Team for quite a few first halves. This is exciting. But, usually, your excitement is tempered by the fact that you have seen it so many times before and that, in the past, it has tended not to end too well.
Of no other "Major" International Side can it have been said so often that "they scored too early": "first half good, second half not so good", as Sven used to say. The penultimate paragraph of the Guardian's match report reads: "England, without any warning, had lost their composure, making basic errors and forgetting how to take care of the ball". Of course, you're thinking, we've seen this before. Indeed we have. But if you want to commentate on England matches you have to forget that. STAY IN THE MOMENT!
Continuing from this: you MUST - this cannot be stressed enough - ignore any and all warning signs. Are touches becoming inexplicably heavy? Is Steven Gerrard raising his artillery? Has Wayne Rooney just flicked the ball off his own thigh and out for a throw-in? Has he stamped on Danny Wellback? No matter! Deny the evidence of your senses! You have forgotten the past already, of course, so don't worry. It'll be fine. England will soon be the slick and shiny, white-clad pass-and-move machine that started the game. Why wouldn't they be? Exactly.
With the basic principles -- George Orwell spoke of doublethink -- mastered, we can move onto finesse.
First, you have to shout Gerrard's name every time he shoots. Rooney too. By all means come up with your own method of enunciation, but remember that posterity is at stake. Convention has it that the final syllable of Gerrard be lengthened -- GerAARRRD -- while it is usual to really bark out the ROO in Rooney. But play around with these: try RRRRRRoonEEEEE out for size, for example.
Second, and no choice here I'm afraid: you have to pretend that Ashley Young is good. You have to act like you expect his introduction to have a positive impact on the game. Practice saying "an attacking change for England" or "Roy Hodgson sends for the cavalry" over videos of Young being brought on for Tom Cleverley. (This is very hard to do).
Third, and here you do have choice again: cultivate a personal sort of vague and seemingly-suppressed prejudice. The two most common routes here are the Motson and the Tyldsley. The Motson (or "Motty") requires the bald use of stereotyping: Brazil DO NOT defend; Italy don't do anything else; African goalkeepers ARE bobbins; Englishmen are very brave; foreigners, less so. Alternatively, you can take the Tyldsley route and continually compare places to England: "you can't imagine this going down especially well in the Barclays Premier League" you might tutt; or, "I wonder how her Majesty's constabulary would deal with that young entertainer"; "Down with this sort of thing"will be your general approach to Foreign. Frown.
Fourth: Ashley Cole is the best left back in the world. Got that? Good.
Finally, and here we get to have some fun: apportion lots of blame on a single individual. When something bad happens, when something does not go quite according to plan, it is of primary importance that your viewers know, exactly and unambiguously, who to blame. So, pick an individual -- yes, ONE person -- and heap all responsibility remorselessly on their shoulders. The manager is always good for this, and the captain can be an effective scapegoat too, but the best, the absolutely ideal, villain will always be the best player.
Keep this framework in mind when selecting your opprobrium mule: the higher the individual's profile, the better. Fifth-choice centreback? Hmm. Manager? Good. Absent erstwhile skipper? Better. Only truly elite player? Best. Within this, though, its important to remain circumspect. Young hopefuls, for example -- the kind which will allow you to moralise that, "Well, he really does still have a lot to learn" -- are useful beyond their current status because of the potential that this moment could come to define a career. (Theirs, of course, but it's not going to harm yours -- which is, of course, the most important -- should yours be the first or final sentence).
And this brings us to the end of the lesson and the crucial, final keynote: always moralise. Be as sanctimonious as you possibly can: people should, frankly, be hanged for booing national anthems; flares are incredibly dangerous. Remember that at all times you are the spokesman for a great and proud nation. You must never lose sight of this responsibility nor awareness of the reflected greatness. Your job is not, ultimately to describe, not even to comment but to judge. Everyone. And therefore I say again, I stress: ALWAYS MORALISE.