It hardest to train on is defense. One simply has to have someone to play against.
There really is not anything quite right, as everyone has their own variations in the defence. But there are things that are better than others. Something you have to remember is that you can not defend against everything all the time, but you have to adjust the defense for what the opponent is going to do.
The first thing you need to work on is the goalkeeper. The starting point for goalie work is to stand with the goalkeeper in the middle, with his back outwards. As reflected shots hitting the goalkeeper, replaced with rims and not straight to the opponent’s center. The defenders will have their main task of keeping close to the posts. This tactic is called box. This will often be sufficient very far, but not all the way. Passive defenders standing close to the posts always give free way of passes in to the center. Is the opponent good at making centers tricks, he will make many goals anyway.
That is why does most players have more active defenders. Everything from active box to what we called Flipper defense. Flipper defense is based on the keeper covers up the pole closest to the puck and the defenders higher up in the field to cover the passageways. Most elite players playing a combination of Flipper and Box. Which you prefer and how much use is made of the two extremes is different from player to player.
It is best to start with Box for later when you can read your opponent move to more of Flipper.
Regardless of which version you are running, you will always have gaps. Witch gaps that you choose to close all depends on who you meet. If the opponent is very good at making quick Shovels so the Box is to be preferred. If he does not so accurate on the shovel but a bugger to make center tricks, then it’s Flipper to apply. Defenders must be up and disrupt the pass.
So think about where you have the goalkeeper. When you also released goalkeeper in assault operations, make sure he stands in front of the goal and not at right angles to the post. Then he can save one or two random shots of himself.