It just occurred to me, after demonstrating how to kill a legged opponent to a new fighter, that I had completely missed the topic of shield work on here. Most early training focuses on defense and a few basic strikes, but often misses the utility of using a shield on the offense.
I realize some of this needs to be elaborated on, or at least needs pictures. I'll see if I can't get around to updating it soon*.
Knocking people over can sometimes be the simplest way to finish a fight or break a stalemate. Unless your opponents are pretty decent with the wrap shot while falling, a good shield bash can leave you with a variety of openings to exploit. If you manage to knock then down, their legs will become the obvious targets. If they keep their footing (or stay up on that knee), you might get a chance to hit an opening as they use their arms to balance, thereby opening their guard slightly.
One thing to keep in mind while bashing is that your shield will have a tendency to rise while extending your arms. This gives you a good chance of bashing someone in the face, or pushing their shield into it. It is advisable to bend at the knees and then lean into the bash, thus giving it extra power and reducing the chances of face bashing due to the lowered stance. Placing your sword hand behind the shield and pushing will add a little extra stability.
The risk with bashing, is that you bring the plane of defense inside your opponents threat range. This makes it much easier for swings to get around your shield. Placing your bash slightly off-center, towards the opponent's sword, mitigates some of the risk. Regardless of precaution, wrap shots are still deadly at this range.
Shield contact is useful for moving the opponent's guard. Doing so without closing in to bash is often safer and can prove more effective. The key to a good shield punch or check is to move their guard while cutting off their angle of attack. A punch to the sword-side edge, for example, opens their shield side to attack while pushing their sword side back. Because of the position of the shields, their only clear targets are your shield leg and a high cross to the chest.
Checking their sword side is much safer, as their offense is pushed away and the angle of attack is more in your favor. Checking to the shield side is more dangerous (except in the case of lefty vs righty). When checking the shield side, your defenses move over, cutting off much of your own angles while offering your opponent a clear shot at your shield shoulder
The angle of the shield during a punch is usually vertical, hitting along the slot between their sword and shield. This causes the opposite edge to open up. Changing the angle changes the opening. Punching at a 45 degree angle along the top (read: dangerously close to face) opens the bottom edge to a hip wrap. Punching with the edge across the face of the shield acts much like a longer ranged bash, but opens up even more of your lower body. Punching downward (trying to catch some of the sword side curve on a round) sometimes lowers their defense against high crosses.
A rip is using the back of the shield edge to pull open the opponent's defenses. By itself, it is fairly risky, greatly exposing your chest to high crosses or stabs from down swords. The range is much closer than more shield work, excluding the bash. I find that leading into the rip with a short cross to their sword while closing the distance to be quite effective. If you are lucky, the cross will force their sword into the path of the rip. In that case, the rip will turn all of their defense to their shield side, allowing you to easily dispatch them with a high cross.
If you miss the sword, they have two options. They can attack your shield side (which will become exposed as you follow through), or they can defend their exposed chest. Attacking means they will still be open to the high cross. Defending will negate the risk, but only serves to reset the fight into a very close range.
A note here, they can counter the rip with a short cross or high cross, potentially killing you or tying up your sword. Mitigate your risk by executing the whole combination (cross, rip, cross, for example) quickly. The less time your opponent has between steps, the less likely they are to counter.