As somebody who has beaten Gothic 2 8+ times I can assure you that each following style is better than the previous one thanks to increased speed and decreased recovery times. Once you play around enough you will notice how much faster you can recover, swing and cancel one action into another.
When fighting animals you should attack like this: first 2 combo hits, side swing, first 2 combo hits, side swing, repeat until the target drops dead. The reason for using 2 combo hits into side swing and not just swinging left right, is that doing combo hits advances you towards the target, the creatures in Gothic slip away slightly when they are hit, they can still slip away from you even if you use the said technique, but that way you will be able to land much more hits before they do. You should never use more than the first 2 hits in a combo, no matter your mastery level, the following hits are just way too slow and take too long to come out.
When it comes to humanoids you should never attempt to hit them more than 2 times in a row, unless you are willing to trade HP, because they will hit you back, and getting hit in Gothic hurts a lot. What you should do is use the first hit of the combo and cancel it into side swing immediately, after that parry, dodge backwards. The timing is pretty strict and you might not get it all the time.
Once you reach 60% with one handed weapons you can cancel the first hit of the combo into step forward and then do first hit of the combo again, this is easy to loop and you can do that instead of the usual "first 2 combo hits into side swing" stuff. However, this is harder to use on humanoids, I recommend sticking with default "first hit into side swing" pattern.
All of these techniques apply only if you have at least 30% in one handed weapon proficiency, before that you should stick with your 2 hit combo, because side swings are just terrible at that level.
One thing I don't see anobody mentioning during control scheme discussions is that Gothic 1 and Gothic 2 control schemes treat attacks differently. If you use Gothic 1 scheme you can cancel side swings into backwards dodge immediately, but not the combo attacks, for Gothic 2 scheme it's the opposite. Dodging backwards is pretty much the ultimate defensive move in Gothic melee, while dodging you block all attacks in front of in a large cone (something like 140 degrees) and move away from enemy attack range, it also the only way to defend yourself againt animal attacks, only golems, trolls and dragons ignore dodge protection. So if you are panicking or not sure what do next, you can just keep dodging back, you will stay completely safe while doing so. Mind that when you choose a control scheme, of course, you can always cancel any attack into parry and dodge afterwards, but it's way sloppier than dodging right away, and parrying is generally riskier and it doesn't protect you from animal attacks.
Dodge backwards is the prime reason I recommend everybody to play with one handed weapons not two handers, unless they feel like gimping themselves. When you use one handed weapons and dodge back you recover way faster than if you were using two handers, this allows for much, much easier punishment at any given chance. With two handers, most of the time opponents will be able to fully recover after an attack before you will be able to hit them, that is if you choose to defend yourself via dodge. This is especially troublesome when you are fighting groups of enemies, where parrying is risky, or animals, where backward dodge is your only defense options. Another thing is that one handed weapons give you much better miliage once you get an opening thanks to their speed, you will be able to land more hits before having to defend yoursrlf again. Especially if you catch somebody from the side or from behind. And lastly combat styles for two handers frankly just suck until you get to 60% and that's a long road, especially in comparison to one handed weapons that become good at 30%. I guess Wulfgar says that you have to plan ahead when using two handers for these reasons specifically. Generally speaking, the small increase in damage per hit and length that two handed weapons get just does not worth the downsides that they come with.
And lastly I always tell people that Gothic melee combat is about pattern recognition. Don't try to just react to attacks, they come out way too fast for you to able to do it and the telegraphed ones (trolls, golems, dragons) usually can not be defended against. I remember some russian modders said that side swings hit the target pretty much instantly, even before the weapon reaches the target, you just don't notice that while playing, because the animations are so fast. So, instead you should predict when the enemy is going to attack, recognize the pattern, defend yourself, hit back. Take Moe, for example, the thug near tavern in harbor district, his pattern is the most braindead one in the game, he will always attack back once after taking a hit. So to beat him you just do this: hit him once, parry, hit him once, parry, hit him once, parry, repeat until he drops on the ground. Easy, you can do that with your eyes closed. Of course, it gets more complicated, for example, orcs have something like 4-5 attack patterns, but once you get familiar with them, it will be easy for you to recognize the oppenings and punish them at the right times.
I hope it helps
Zanzoken and anybody else who reads this.