The technique for taking a shot is somewhat awkward to master at first and rather tough to describe (it puts one in mind of the difficulty of describing spin bowling with mere words), but we shall try, and make the assumption that we are speaking about a right handed player. First, you wrap the string around your right hand until a suitable length for making the strike remains. The exact length is up to the player and will be selected as a function of how good one's aim is and ultimately the degree of force one wishes to impart, but about six or seven inches would seem normal. Second, with the left hand one holds the conker, palm upwards, with the string itself taunt and passing between index and middle finger. Third, one takes careful aim and some may want to visualise the shot. This is also a good time to caution your opponent to hold his conker dead still. Fourth, one swings down his or her conker onto the opponent's conker with as much force as can be mustered from a sort of over-arm flicking motion of the right hand and arm (this action is akin to a fisherman casting out a line). With luck you will have hit and your opponent's conker will already be showing signs of weakening. Miss the shot; you've probably just hit yourself with some degree of force in the crotch with a speeding conker. Stiff upper lip and keep a brave heart, for the game goes on. There is some debate as to whether it is best to aim to inflict incremental amounts of damage and generally wear down your opponent (Ali style perhaps) or whether it's best from the outset to "come out swinging" (but risk missing all together). This difficult judgement call is one that the conker player faces on every turn and there are no easy answers.
Equipment
Your entry into the world of conkers requires two items; a conker and either a short length of string or -- ideally -- a shoelace. Garden twine we can put to one side immediately, we need something a bit stronger than that. The conker itself is of course in essence a hard brown nut that falls off the Common Horsechestnut (Aesculus hippocastanum) in a spikey outer skin which protects the fruit in its fall to the ground. The sweet variety are of course edible (albeit that they can induce incredible degrees of flatulence), but we are concerned here with the inedible version which we prize for its solidity and hard shell. Procuring a suitable conker is all part of the fun. One might for example attempt to find one on the ground, but real experts much prefer to vigorously throw sticks at "Conkertrees" and see what falls down.
Your next task is to pierce a hole in the conker through which the shoelace can be threaded. Various implements may be used but I've personally had a great deal of success with those small spikes one uses for holding corn-on-the-cob in polite company or alternatively, steel skewers. Anyhow, hole in conker produced, tie a knot at one end of the shoelace and thread the shoelace through the conker. A few fiddly moments later you will be equipped with a fully functional competitive conker. Perhaps it's not as competitive as it could be though...
"The Competitive Edge"
Cheating at conkers is clearly the behaviour of a cad and a bounder, but at the same time one of the great delights of conkers (and probably the most discussed aspect of the game) is thinking up ways to get an edge. Many conker players find this duality difficult to manage at first; by day one is a noble nut-related pugilist fighting honourably until the death, but by night one is forced to become a crazed scientist or worse, as indeed superstition probably plays a greater part than reason for many. Probably the most widely explored technique is attempting to pickle the conker in vinegar. In my view this is a disastrous tactic. Not that I would ever consider playing with an adulterated conker, but often one will find the conker immersed in vinegar to actually lose rather than gain strength and general hardness. Alternatively, one might also try to bake your conker in the oven. Inconclusive. Clearly one can go too far with this, one is not looking to produce a charred husk. But I have come across baked conkers that were indeed impressively hard. In the netherworld between urban myth and the stupid stuff schoolboys can occasionally get up to when an obsession strikes a range of other "treatments" have been devised to enhance the basic conker. These range from the use of polishes and varnishes (said to strengthen the shell and also by smoothing the shell giving your opponent's shot less "grip"), and the strategic use of superglue, to rather fanciful tales of rocks painted to appear like conkers and faux-conkers carved out of a wood with a similar grain.
Whilst not really as much fun as hare-brained scheming, there are two sure-fire ways to get a good conker. First, assuming you have got your hands on a batch of candidate conkers, simply drop them into a bucket of water. The denser (and thus better) conkers will sink to the bottom. Hand out the "floaters" to friends. It's a nice thing to do, and you can also use these lame ducks to quickly build up your score (see below). Second, older drier conkers are often superbly strong. The difficulties here involve having the foresight to store them (and find them again the next year) and also finding somewhere suitable where they will tend towards drying out rather than shrivelling or rotting.
Scoring
One of the best features of conkers is its scoring system. An individual conker (not the player) will over its career go by different numeric titles. The shy debutant conker in its virginity is termed a "none-er". The general formula is that you add your opponent's conker's score to your conker when you win. If our new conker meets another new conker in competition and prevails it becomes a "one-er". Then if our one-er is used and pulls off a coup comparable with the end of Rocky II and smashes a ten-er, it becomes an eleven-er. [Although some may dispute this and claim the formula should be value of conker + value of defeated conker + 1, possibly this is a matter of regional variation]. It is this scoring system that gives a game of conkers a sense of occasion. Bear in mind a game of conkers is effectively a fight to the death, it's a spectacle indeed when, say, a fifty-er is put up against a thirty-eight-er. For this reason it is not uncommon for players to affectionately retire championship conkers in the event they begin to show signs of damage. A conker's score is not formally recorded in anyway, it is an issue of honour. A high-scoring conker with reasonable provenance can occasionally be traded within various informal economies for crisps and comicbooks should you so desire.
Schoolyard rules [The nasty stuff]
If it has not already been made clear, conkers is a tough game requiring grit, determination and the ability to get away with the cheating you would never dream of doing in the first place. Crying will get you nowhere. With these warnings out of the way we can discuss two important rules that you may not find officially noted or discussed in polite company but that are universal in the street level version of the game. The first concerns what happens when the strings twist round each other as will happen now and again. It is not uncommon at this point for both players to attempt to tug on their respective strings to unknot them. Egregiously, some players have been known to do this with something of a snap of the wrist, attempting to inflict a little extra damage on their opponent's conkers weakest point (the hole in the top of the conker). This is perhaps analogous to a boxer throwing an elbow when coming out of a clinch or perhaps a high-knee in a Rugby scrum. Nasty stuff.
An additional rule when the conker strings are tangled is that a shout of "strings" (posh kids) or "tangles" (scum) or regional variation thereof (the Welsh probably make some sort of gagging sound as per usual) gives the first person to make it the next go. Second, there are the rules that cover what happens in the event your conker ends up on the ground. This is a dire situation and speed is of the essence if you are to have any hope at all. A call of "stamps" will give the attacking player the absolute moral right to destroy your conker by stamping on it. This is not pretty, pulp goes everywhere. It's a shitty way to lose an otherwise rock solid high ranking conker. However, if you can get a cry of "no stamps" in first, technically at least your conker is safe. Quick, snatch it back up or even kick it away from your opponent's size 9s if need be. As I've already mentioned, the Autumnal wind can be a real problem when playing conkers and never more so than at times like these when it can be quite deafening.
I mention the dark underbelly of the game here so that you can be streetwise about it. Heaven forbid you should use these techniques yourself. So, beware the player who seems to deliberately miss with some vigour and instead gets the strings tangled. He might be trying to get a few low blows in; he might even be playing for Stamps.
Safety concerns
Conkers is a potentially dangerous game. You could get hit with a speeding conker in any part of your anatomy. Your hands almost certainly will get whacked a few times. For the terminally clumsy a cricket "box" may be a good investment. Your hand might get stamped on rather hard if you are attempting to rescue a conker from stamps. Shards of exploding conker might hit you in the eye. Apparently conkers are poisonous if eaten, to the extent that whilst deer can just about consume them, horses cannot and will not. So, you've been warned. If you feel it necessary, by all means turn up in your "Gridiron" or Ice Hockey outfit and feel safe whilst partaking in your sport. I'll laugh at you for being a pansy though.
Conclusion: The Joy of Conkers
As we have seen then, conkers is the game that has it all, something that creates more than a few paradoxes. The equipment to play it with is universally available and effectively free, yet one can spend weeks, months and even years mulling over ways to improve upon nature itself. Conkers is simple enough in its mechanics, but getting a good, accurate and forceful swing when taking a shot is the work of a lifetime potentially (as it is in golf). Conkers is a game in which both small boys and men are asked to be gentlemen, indeed, female players are asked to be gentlemen as well. Yet conkers is a game rife with cheating, allegations of tampering, and all the possible brutality (stamps, tangles etc.) that can appear in an un-refereed full-contact sport. Whilst on the one hand a banal way to spend an Autumnal afternoon, perhaps conkers is even a metaphor for life, the turn structure invokes the difficult lessons of give and take. I love playing conkers, and I think you should try it as well, it is the true Sport of Kings (and small boys, and everyone in between).