Getting your exercise through a workout boxing bag is good for a number of reasons. It builds strength, helps tone your muscles and is a good cardiovascular exercise.
As with all workouts, you should do some gentle exercise first. Although there is not a lot of speed involved, it is always easy to damage a muscle. You can also buy the best punching bag from companies like https://everlastonline.eu/es/boxeo/sacos-de-boxeo.html.
You should make enough to work a light sweat, and make sure that you exercise your limbs like legs are still to be tense, even if they are your arms and shoulders that are most of the movement.
Your hands should be protected at all times. Bare Knuckle fighters may flinch at the idea of wearing gloves, but it is not for the average participant.
In particular, make sure your fingers are protected. As the warm-up that you just made, start slowly. Make the first few punches quite light, then build more powerful hard blows.
Try kicking the bag time to time. Unless you are really flexible, you may not be able to reach up the bag, but the more you practice the more you will be able to hit.
Keep bouncing on the balls of your feet. This will allow you to be better placed to hit the sack as it moves and keeps your heart rate. That's why it is so important to warm up beforehand.
As you learn how the bag moves, it will help with your leg movements. There is no need to take a small bounce back and aim a punch if the bag swung away from you.