I'd consider myself a pretty damn good manual blocker and player in general. I've played since Warband was in beta, and there was a stage where I didn't know how to block at all. To be completely honest with you, I think trying to learn to fight without blocking is very important, only because you can learn a lot from it. It taught me to take full advantage of the range and speed of a weapon as well as using proper footwork to fully utilize, well, the range and speed of a weapon as well as punish others for their weapon choice. Obviously since this is cRPG (I learn on Native and I honestly don't really even play cRPG much), and there are so many different variations of builds and weapons, those kinds of things are less important and more difficult to learn playing cRPG, but they will really help you a lot in the end.
Eventually, I gradually learned the importance of manual blocking and I started to be able to parry blows when I made a mistake, or the other guy was a good blocker. The only real way to learn to become good at it is practice. Start by just focusing on left and right slashes, then when you master defending against those two directions, throw in chop and stab. I'd also recommend trying to train yourself to make less intensive mouse movements when you are blocking AND attacking; that's what took me the longest to get over and what helped me the most. I can't tell you how many times I blocked a hit, but then turned too much and thus couldn't block the next hit.
After you learn to block, start focusing on the mind games. The only way to beat a truly solid player is to do something out of the ordinary in order to beat him. Feinting only works to some extent and only on less experienced players. Learn to do things like hit in one direction multiple times, then feint a stab, but chop (chop seems the be the attack that most lesser players just can't block, as a side note), that's a really basic example. Do things that you know would trip you up. The most risky, yet effective way to kill a good player or a good block is with good footwork and shit. That's where the footwork and shit that I was describing in the first paragraph comes in. If you know the speed and range of your weapon, you can beat a solid blocker by using the speed and range of your weapon to your advantage.
I hope that helped a bit. Just realize that this is a game where you really need to practice to get good. It may seem really simple at first, but there is a ton more depth then you could ever realize at first if you actually want to become good at the game.