Well, keep in mind that I only have a passing familiarity with boxing, so if you really want to write it, you’re going to have to do more research. (And you should always be doing more research anyway because the information you glean from one source is never as the one you gain through your own work.)
Boxing is one of the oldest surviving Eurpoean martial forms and has been part of the fine tradition of gambling for many centuries. However, training in boxing has currently passed almost entirely into the realm of sport fighting and out of the realm of traditional combat. Today, boxing can be learned for self-defense but most of those who practice it do so to either become a professional fighter or for health and fitness reasons.
You may be wondering, what does the history of boxing have to do with writing it? Well, like civilization itself, combat evolves. How I would write boxing in 2013 is very different from, say, how I would write a character who boxes in 1908, or one who boxes in 1803, and so on. Fortunately for you, however, boxing is a sport that is very well documented. I recommend some research of it’s history if you haven’t yet, mostly because it will help show the kind of characters who become professional fighters, the tradition of boxing in the “Western”/European/American military, and of course, what the culture that surrounds modern boxing.
Remember, it’s not enough to write a character who can box, you also have to create a realistic persona to go with it and a surrounding back story that supports them. A character who started boxing as recreation at their local YMCA is going to be very different from the character for whom professional boxing was the only way to escape poverty, and they both will be different from the character who learned to box at college and worked the collegiate sports circuit (and whether that was East or West Coast in America), they will also be different from the character who started boxing because they joined the Military and went to one of the officer Academies like Westpoint where boxing is a tradition.
Okay, so let’s talk about boxing.
First, I want you to check out this post: FightWrite: A Basic Upper Body Primer (Fists) because it does cover some of the basic punches and how they work.
Boxing is limited almost entirely to the upper body, with the exception of knees, and, in a modern context, almost all the strikes are based around the assumption that your hands are wearing boxing gloves or, at the very least, some sort of wrap for reinforcement. A common beginner mistake is assuming that the boxing gloves are there to protect the opponent’s face, they aren’t. They are there to protect the hands from a metacarpal break (fracturing the fragile bones in the fingers). A metacarpal break is commonly called a “boxer break” or a “boxer fracture” for this reason, a broken finger bone is a common injury for a professional boxer. The incidents of serious head injuries actually increased after the introduction of the boxing glove because fighters could suddenly punch to the face without fear of injury.
This is important because this is how your character is going to be trained, unless they receive supplementary training for when they are assaulted on the street, they will follow their first instinct and today, the opening boxing strikes do go to the head.
Because of it’s reliance entirely on the upper body, boxing has to happen in very close quarters aka inside arm range. This means that if the fight doesn’t begin with a face to face altercation then the boxer has to close the distance. Boxers will be at a disadvantage against kickers if they can’t get past the legs and may also be at a disadvantage against grappling experts and joint locking practitioners if they can’t knock them out before they get a good grip on their arms/legs/shoulders/head etc. It goes without saying that they will also be off balance against an armed opponent, especially a knife or crowbar/club/tire iron. That said, boxing would not have survived so long if it was not an extremely effective martial form and, also, fun to watch.
The Fighting Stance: The fighting stance for boxing is a very square one, both shoulders face the opponent on an even line, the back foot is on the ball and bent at a 45 degree angle. The boxer leans forward slightly on the front foot, tilting forward, ready to spring into action. Both hands are up to protect the face, with the fast hand (usually the left) slightly forward with the right hovering right at the cheekbone. The power hand (right or left) will always match the foot that’s tilted onto the ball, because of the greater hip rotation provided by the pivot of the back foot.
Blocks: Boxing blocks are very simply and are great when studying conservation of movement. Unlike some of the more traditional martial arts that use big movements, blocks in boxing rarely move much. They involve batting and pushing the incoming hands away from the face, freeing the fighter up to retaliate quickly. When they need to protect the head from a high strike like a haymaker, the fighter tucks their elbow up against their head in a triangle to take the incoming hit.
Slip: The slip is when the weight drops and the head tilts slightly to get out of the way of an incoming attack. A slip will often lead into a hook or an uppercut, because the lower positioning of the body allows for greater rotation of the hips and puts the fighter into a position to easily attack the ribcage.
The clinch: When the fighter gets in close enough that he can wrap his hands around the back of his opponent’s head, the clinch is often accompanied by powerful knee strikes while the other fighter attempts to defend himself from a disadvantaged position.
The jab: This is the opening punch used to soften up an opponent’s defenses before delivering a cross. The jab is always the front hand or the fast hand and while it doesn’t deal much damage, it can pound away on an opponent to create openings for much stronger attacks.
The cross or the straight right: The cross is the back hand or the power hand, this punch achieves a full rotation of the hips. It’s slower due to the windup, but is much stronger. In a professional fight, the cross often aims for the cheek, the nose, and the eyebrow (to cause bleeds). These attacks correspond to the same side as the punch, so one fighter’s right connects to the fighter’s left side of their face.
The hook: the hook is a punch that comes across and aims for the ribcage. The hook can also go high, if the opening is right, and aim for the back end of the jaw to the gap between the jaw and the rest of the skull, right beneath the ear. A successful hit here will cause a knockout.
The uppercut: The uppercut is a punch that comes up, underneath the jaw or drives into the stomach/solar plexus region of the body.
Elbows: I think boxing allows elbow strikes, these usually go to the face if the opponents are close enough for them.
Shoulder check: ramming the shoulder into the chest.
Hip check: ramming the hip into the opponent’s side, when on a horizontal angle.
Strategy: most professional and collegiate fights rely on a significant amount of strategizing pre-fight for success. A similar kind of strategy will be at play if the fighter finds himself or herself in combat on the street. So, it might be worth reading through a few memoirs and how to books to get a solid feel for what the basics of those strategies are. You want to write a boxer, you’ve got to write a character who thinks like one.
There’s a lot more to it than this, but this should be enough to get you started. Also, do yourself a favor and start learning the differences between professional boxing and Olympic boxing. Then, watch some professional fights if you haven’t yet. You can find quite a few for free on Youtube. Have fun!