I decided I would start off my advice with an overview of the different punches used in boxing. So here it goes, hope it helps.
Jab- The jab is the most used and most important punch for any boxer, your ability to throw this punch well can literally make or break you. The jab can be used to separate and make space or used as a normal punch to hurt your opponent. It is the lightest and quickest punch of them all. Execution: Start in your normal fighting stance with your hands guarding your face, you should then extend your arm straight forward and "snap" it out in front of you. This should all be one quick motion and your hand should return instantly where it started after it is executed, and should be almost all arm with no body put behind it.
Straight- The straight punch is a strong damage dealing punch that is used mainly to do damage. It is much riskier to throw than a jab because you will be leaving yourself open for a longer period of time, but if the gamble pays off and a strong straight punch is landed it can be deadly. Execution: should be thrown similar to a jab but now you will put your whole body into the punch and rotate at the hips. As the name implies the straight should be thrown in a straight motion.
Hook- The hook is probably has the most potential to do damage and is the most capable of creating a one hit knockout. It is risky because it will leave your face open, but can really pay off if landed flush. Execution: The hook should be thrown usually at the end of a successful combination or when the opponent leaves themselves wide open. your arm should start in its normal position and then come in a hook motion and strike the opponent on the side of the head/body. You should twist at the hips and and put a lot of arm and shoulder into this punch.
Uppercut- The uppercut is another high damage dealing punch if landed hard, it can be absolutely devastating. The uppercut can be best utilized when an opponent is leaning in, which is common into the later rounds as a fighter gets tired. Execution: The uppercut is thrown with the hand starting low and then coming up in a swooping motion so as to catch the opponent on his chin or upper chest. The arm and shoulder should be utilized as well as the legs.
This is just a brief overview of the four basic punches, you will need to master all four in order to become a good fighter.
