My game improved a fair bit after about an hour on the duel server in vent with people willing to help. I learned stuff that I never adequately grasped during my entire first generation character's career.
For example:
Left-to-right swing (backhand swing)
This is your quickest attack and is best done while simultaneously stepping to the right of your target, as if you were going to run past him, then pivot to face him after your attack lands, block his counter-attack and repeat. This is why you often see two people spinning around each other when they fight -- they are both doing the left-to-right swing with a step to the right, which causes them to whirl around each other. If you don't step to the right of them as you swing, your attack will take longer to land and spammers will get you.
Right-to-left swing (forehand swing)
This is a longer reaching attack, but is slower to land than a backhand swing. I use it against backpedalers (where left-to-right wouldn't have the range to hit them), people who turn their back and run away or to try and get a surprise hit on someone that's closing with me. It's my least used attack.
Overhand swing
This is inferior to the backhand swing for fighting someone 1 on 1 but it's a great way to bonk someone on the head with little risk to your teammates. I mostly do this when I come into a 5v1 melee where the 1 enemy is snaking his way through the crowd and the crowd is mostly killing each other with stupid side swings. I ready my overhand and wait for the guy to snake past me and wham, right in the head.
Thrust
Use this similar to the overhand -- not for 1v1 combat so much as for group combat where you want to avoid slicing teammates, or to reach someone that's too far away for a backhand. It has good reach.
Also be aware of the "hold" maneuver. Consider the following scenario:
* You whack his shield
* He whacks your shield
* You whack his shield
* He whacks your shield
* You hold your attack for half a second, then release it
* He detects a pause in your tit-for-tat rhythm, sees it as an opening, goes to swing and them wham, your delayed swing hits him.
2H spammers often don't bother with this but shielders do it frequently. Don't wait for him to attack -- just establish a rhythm and then throw in a delayed swing to throw off the rhythm. Don't do this every time -- keep them guessing by doing it maybe 1 time in 3.
Your best bet against the 2H spammers, though, is the backhand swing and step maneuver. Delayed swings won't work against spammers because all they're doing is swing-swing-swing-swing-swing-swing-swing. A good backhand-and-step, though, can often get in a hit faster than them and sometimes you can get in two or three hits before they realize they need to stop spamming and get in a parry.
Another thing to think about is to just hide behind your shield more and attack less, if you find yourself getting creamed while your shield was still full health. By making someone bang on your shield for 10 seconds, you may be delaying one of the enemy's top players, and the longer you hold them off, the greater the odds are that someone will notice what's going on and help you.
At any rate, I think the best early thing to understand are the differences in the swings. Newbie mistake #1 is probably just alternating the 4 swing directions without realizing the differences between them. Forehand swings in a 1v1 duel generally do nothing except get you hit.
Also, you might try something like a Nordic Short War Sword or a Wakizashi. The damage isn't great but the speed is. Once you can start landing blows with those weapons, then try switching to some of the slower, harder hitting weapons and see if you can adjust what you learned to them.