Reddit mentions of CAP Barbell Black Neoprene Coated Single Dumbbell, 10 Pound

Here would be Freddie Roach explaining basics: https://www.youtube.com/watch?v=WmgHY6rk0QE
https://www.youtube.com/watch?v=uUTWcGol3CY

Yes, I know he talks a bit funny (it's a health issue) but he absolutely knows what he's talking about. He has trained a lot of boxers and some MMA fighters. Most notably he's Manny Pacquiao's trainer. https://en.wikipedia.org/wiki/Freddie_Roach_(boxing)

General tips:

• Always turn over your hand completely while throwing jabs, straights/crosses. i.e. make it horizontal. With hooks it depends which hook you're doing, some are done with a turned over fist, some with a vertical fist.
  
  
• Always tuck your chin in and hide it behind the shoulder of the arm that is throwing the punch.
  
  
• Don't admire your punch even if you land it
  

• Move your hand back as fast as you've thrown the punch
  
• Move your head or reposition immediately after throwing a punch
  Failing to do so makes it easy to punch you
  
  

• Never have both arms extended, always punch, retract your arm to protect your face and then throw the next punch, even in combinations.
  
• Change levels. Go upstairs, downstairs, mix it up
  
• Make a good fist, let someone/your instructor show you how to make a good fist
  
• Don't ever splay your thumb, it's a sure way to break it. I know a few guys who had that happen to them. Keep it tight and have it support your fingers
  
• Try to hit with the knuckles of your index and middle finger. Hitting hard with the other knuckles might result in a broken hand.
  
• Don't punch the face without gloves. Use your palm for strikes to the head. Hitting bone can result in a broken hand
  
• Hold your wrist straight. With a straight punch keep your arm completely straight. If you don't your writ or elbow may break on powerful impact
  
• Rotate your hip, pivot on your back foot. Punching power comes from your whole body working the punch, not (only) from your arm. In boxing there's the term "arm punches" for punches that have no body weight behind it - those hardly ever do damage
  
• punch slowly at the start. Try to get the motion right. Try to be precise in where you hit. Use a mirror and take yourself as the target. Speed will come in time when your form is good. Things you can do slowly you can learn to do fast - things you can't do slowly are a disaster if you try to do them fast.
  
• Try to master the jab first. And last. And always. It's not meant to be a hard punch/power punch - it's a range finder, it's used to position your opponent. To disturb him. To blur his vision. To set up power punches. It has so many uses, it should be your best and most versatile punch. Learn to hook from the jab. It should be fast and precise and busy - it's not primarily meant to hurt your opponent.
  
• "Don't hook with a hooker" - if you fight someone who relies a lot on hooks, who primarily throws them: don't hook. Use straight punches. A skilled hooker/hook specialist will hurt you when you try to hook with them
  
• Punch with a purpose. Don't punch just to punch, think about what you want to achieve. If somebody hides behind a high guard make them open the guard. Punch to the body, get close and use uppercuts. Don't keep punching onto their guard just to do something. Try to come up with a strategy and follow it.
  
• Punch your mattress (not too hard) to test if your arm and your wrist are straight. If they are not you'll notice your wrist giving in and your hand changing position. It has to be a solid union else your punching power is lost and you're going to hurt yourself.
  
• train your wrist. I like to punch with neoprene dumbbells like those: https://www.amazon.com/CAP-Barbell-Neoprene-Dumbbell-10-Pound/dp/B00UM41N9G/ref=sr_1_6 nothing too heavy, 2kg at most. Punch with them and hold them in your hands while moving your hand up and down. You need strong wrists.
  
  OK, that's all I can think of off the top of my head. if something's unclear feel free to ask.
  
  Oh, and PS: If you fight somebody who knows what he's doing - never circle around them towards their strong hand. You'd be walking right into a hook and as you move into it it will be devastating. With someone who is an orthodox fighter (left hand forward) move towards their left side. If you're fighting a southpaw move towards their right side. If you are forced to move towards their strong hand don't go in a circling motion but move away from their strong hand by moving laterally instead of circling
  
  Another PS: Keep your feet apart. When moving forward push yourself forward with your hind leg. Don't ever cross your legs while moving around, do measured steps. If you square up or even cross your legs you can lose balance easily.