Tactics

This paper contains comments on tactics and techniques to be used for a variety of specific situations, but the advice in the various sections will likely be generally useful to any fighter.

Short Fighters

When you're belly-to-belly with a larger fighter, you are pretty much stuck there.  It’s difficult to disengage, and while there, you are more susceptible to your opponent’s techniques that rely on size and weight.
From the proper range, you can move in and out, alternating between effective longer-range techniques, and effective shorter-range blows - often in the same combination.  You can also move to the corners of your larger opponent, either using his/her shield to your benefit, or moving into the sword side, at an awkward angle for your opponent to either block or strike.

High Targets

This is easy on the first shot - you just aim up.  Lean back very slightly and dip your sword shoulder as you swing, and aim up at the target.  The blade should follow the plane defined by your shoulders, and move up immediately. 
Don’t move your sword hand up, and try to swing from there.  This puts too much torque on the arm.
Getting the subsequent blows up is a bit more difficult.  The way to do this is to angle your returns down.  The arc that the blade makes when you are doing a return defines a tilted plane, with the low part of the plane at the start of the return, and the high part at the target.  If you continue your return into the next swing, your next swing will also be in that plane, at the top part.
Once it is established, you can raise or lower that plane on a vertical axis (relative to the plane of rotation), but you cannot tilt it.  Effectively, you are moving to a parallel plane.  So, if your sword tip is moving down as you start your return, it will be moving up when it comes around to the other side of the circle on the tilted plane.
The power on these swings should be applied mainly during the initial part of the return, rather than at the end.  Once the sword is moving forward past your shoulders towards the target of the second blow, allow your hand to follow it up to the higher targets, rather than pushing with your hand.
Whatever you do, don't try to move the blade from forehand to offside while your hand is in front of you.  This causes a lot of stress on the elbow and shoulder.  Yes, you can do it, if you have strong arms.  The other thing you will likely have, after a few years, is bad shoulders and elbows.

Single Sword

I would not recommend changing your stance to sword-foot forward, but you should reverse your stance, if you are now fighting with the opposite hand.
I partially open up my stance, so that if you draw a line towards your opponent, and draw a perpendicular line across under your body, the heel of my shield foot and the toe of my sword foot are touching the perpendicular line.
In placing my sword, I start from the normal position shown in my manual (sword hand above or just in front of my shoulder, and my elbow back and held high).  Then I raise my sword hand so that it is about level with the top of my head, and the sword is slanted up and over my head, pointing up towards my shield side.  My sword shoulder remains locked.
Blocks are executed by moving the sword hand directly to the point of the block, while trying to avoid moving the blade sideways.  If you can move the sword so that the tip of the blade doesn’t move much, until near the end of the motion, it’s faster and more efficient.
The power for both the blocks and the swings should be supplied by turning the body, with the abdominals tight.
When you execute a block towards your shield side, your body is now “wound up” to swing a backhand blow at your opponent.  If you execute a block towards your sword side, your body is now in position to return a forehand blow.  In either case, your might want to rotate your body more than would be usual, to supply more power and speed.
If you are blocking a low blow, lean sideways towards your blocking hand.  Keep your hips inside of your knees, and your knees inside of your feet to maintain your balance and mobility.
When blocking vertical (or nearly vertical) blows, move your sword hand across the path of the incoming sword, but don’t block strongly.  Instead, let the incoming blade push your sword down and back as you deflect the blow, then use the momentum of your blade to quickly bring your sword around into an attack of your own.  Don’t reset to your shoulder – just continue the motion of the sword in a smooth circle.
When you are attacking, try to avoid swinging directly towards your opponent’s blade.  Instead of trying to beat your opponent’s weapon out of the way (which seldom works) or striking directly towards a target, try to set up a kill on the second (or later) blow.  One way to do this is to swing parallel to either side of his/her blade, and about 6 to 12 inches away.   
The idea here is to make your opponent commit slightly to a block, without letting his/her blade touch yours.  This will allow you to continue your unimpeded swing in a circle into a second blow, while your opponent is delayed by recovering from his/her commitment to the block that didn’t happen.
Another way to accomplish the same thing is to swing at downward 45-degree angles, 6 to 12 inches from your opponent’s hilt (or at less of an angle, under his/her hilt).  Again, you should avoid the block, and move your sword smoothly around a curve (like a Teardrop return) into another blow.  You can initiate the movement with either a forehand or an overhead swing, and continue with a curve on the opposite side of the body.
When you are practiced at this technique, you can string two or more successive “missed” swings, which can cause your opponent’s commitment to successive blocks to become more of a commitment, making his/her response to the next swing even more delayed.
During all of this, you should pay close attention to your range.  For the swinging feints, you should move from just out of range to just close enough so that your blow would have hit your opponent’s shield, if he/she had one.  Use a slide step to do this.  For the follow-up blow, you can move in, so that your blade will impact on your opponent.  Just walking into range and playing “who’s fastest” is a low-percentage game.
Another interesting phenomena of range is to consider the following:

The same thing can be done by stepping forward and sideways with your shield foot to the other corner on your side of the square.  This technique is useful against an opponent with or without a shield.
If your opponent retains his/her shield, things get more difficult.  In that case, the use of range becomes even more important, as do the techniques described above. 
It is important not to stay still.  Standing directly in front of a fighter with a shield, and staying there, especially if you don’t have one, is not the best strategy.  Use a lot of lateral movement, using the momentum of your sword swings to move you laterally in the direction of the swing, or to counterbalance a movement in the opposite direction. 

Fighting against large shields

I would suggest moving into a medium-to-close range, where you can use, or easily move into range to use wraps.  In addition, moving to positions just outside of either shoulder of your opponent will provide you with a good base from which to attack.
When you do use these wraps, remember that not all wraps have to be high and vertical.  There are all kinds of useful wraps - high, low, vertical, horizontal, angling up or angling down.  Pick the point where your opponent would have the most difficulty blocking the blow.
I also like to use offensive shield work - mainly presses with the edge of the shield into the face of your opponent's shield.  This type of press gives you a better mechanical advantage.  This will give you the opportunity of tilting your opponent's shield (and your opponent) one way or the other, thereby opening targets.  Often, I will use a thrust to the edge of my opponent’s shield to produce a similar effect.
Pressing on your opponent's shield also gives you something to push against to move yourself more easily to those positions just outside of your opponent's shoulders.  This is important, because perhaps the most important point of the strategy against large shield is movement - and not movement directly towards your opponent.
A similar effect can be obtained by using thrusts (towards the edge of the face of your opponent's shield).  One good way of getting into this thrust is from an overhead return after your first swing.
One thing to remember is that when you use your approach technique, your first blow should be towards an unprotected point on your opponent, or towards his/her sword.  You gain no advantage by wasting your first blow by swinging to the middle of your opponent's shield.
Even if your opponent uses a static sword block in addition to the large shield, there is always a place where your opponent would find it inconvenient for you to target on your first swing.  If he/she does use a sword block, or you swing at his/her sword, the contact will slow his/her next blow.

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Now I get on my soapbox.  The following is personal opinion.

My feeling is that we are engaged in armored combat.
Things that provide an advantage - like large shields, which provide a lot of static defense - should have a price, like much greater weight and difficulty of movement.  Likewise, longer weapons, which provide more range, should carry a similar handicap. 
To be even more heretical, I believe that requiring a price for an advantage should apply to armor, or the lack thereof.  The price for a lack of armor is not as severe when using rattan swords rather than edged steel, so many fighters will pay it for an advantage, thereby taking more of the realism out of the art.  Also, it is common for better fighters to dispense with much of their armor, because they don’t get hit much.  Unfortunately, this practice is emulated by those who do. 
These positions are my own, and are clearly not held by everyone.

Off-handed Fighters

Distance Control

All things being equal, the best distance at which to fight is the distance that allows you to perform your techniques most effectively.  However, things are rarely equal. 
My strategy has always been to fight at the distance where my techniques were more effective than my opponent's.  My techniques are best and most extensive at normal sword range.  However, if my opponent also likes that range, I may move outside or inside, depending on which range best suits me, and least suits my opponent.
For instance, if my opponent has a super-speed snap, the last thing I want to do is to start a fight from in range, where my lack of speed puts me at a disadvantage.
If my opponent is taller and heavier than I am, fighting at very close range is likely not a good option.  For instance, I once had the experience of fighting a much taller fighter with great swords.  My normal technique with that weapon is to fight very close.  My inside techniques are very good, and I am usually at least as powerful as my opponent. 
This was probably true in this case, but my opponent was six inches taller and several dozen pounds heavier than I.  I found myself in the position I preferred, but with my opponent’s forearms on top of mine.  This made it difficult to perform my techniques.  After backing up about one foot, things started working again.
Generally, the better fighters have good outside and inside techniques, as well as those for the middle distance.  Unless you know that your opponent has a weakness at a specific range, take the one that works best for you.