British Go Journal No. 19.  January 1973. Page 11.
J. T. Fairbairn, 2d
There are various methods of counting, each with varying degrees of accuracy and ease of execution. I propose to give below one of the simplest methods. I have found, in teaching many players various ways of counting, that this one is their favourite, being ridiculously easy to operate, requiring only simple addition and subtraction and two numbers to be remembered at any one time.
All you do is count the territories for each player which are unequivocally his. This means you must get rid of all arrogance, wishful thinking or the like. "Unequivocally his" refers to territory surrounded by a wall which cannot be breached (unless of course one player can have 2 successive moves). As for the fiddly bits round the edges, usually left for yose (end-game), work out the furthest possible encroachment into the territory in ordinary move-for-move play, assuming that the p1ayer defending the territory has gote. Then count only the points in that territory which will not have been encroached upon. Remember to do this even though one of you is likely to get the extra points anyway. Dead stones still on the board count 2, captured stones off the board, including komi, count 1.
This counting starts as soon as the first territory is formed and as each new territory is counted the point total is added to the previous cumulative total. (It is understood, of course, that you will keep your score and your opponents score separate!) When it comes to playing out the fiddly bits, if, say, you get 2 points more than you had expected by counting as above, simply add 2 points to your total. If you get less points than you expected, for instance because of oversights, ko, or swaps, subtract that number of points from your total.
The difference between the two players totals represents the number of points one is ahead, and armed with this knowledge you can make very important decisions. For instance, if you are 30 points ahead near the end of the game and your opponent plays inside one of your territories, dont worry unduly about killing him if theres a risk that you might lose all your territory - let him take 20 points and live. You should still be about 10 points ahead. (Dont forget in this connection that if your opponent gets independent life inside your territory you must take 20 off your total but add 2 points, or whatever it is, to your opponents total for his new territory). In brief, when ahead, play safe. When behind, try a swindle!
Now, while this method is simple to operate, you may say it is not accurate. Superficially this is true, since of course such factors as sente, gote, ko, potential, etc. are not taken into account. However, the value of each of these factors normally decreases as the game progresses, so that by the end of the game the method will be almost completely accurate. In addition, perhaps because these variables balance out between the 2 players in more or less the same proportion as territory, in practice the method proves to be highly accurate when applied both to beginners games and to professional games.
The biggest flaw lies in the fact that it does not permit comparison of the values of different plays. However, this can be learned as a separate skill and can be integrated with the method later when the player is ready to learn more complex methods of counting.