When fighting noobs, hold down W nonstop and continuously inside swing/castor/spam at people only blocking when extremely necessary. With enough PS, armor to cause glances, and a good 2 handed or polearm weapon you will murder your way through mobs of peasants, as bad players typically don't read footwork properly especially the bad shielders, to get the correct attack in before you double hit them.
The easiest kills are ganks on people fighting someone else, no matter how good they are if you catch them off guard and hit them in the head you will get a kill or open them up for your teammates to kill them.
High reach weapons rule on battle as you can cheap shot people while staying out of danger, though it is best to fight with space so you don't get your weapon stuck in teammates.
Duel server to hone your muscle-memory block reflexes, reach predictions, reading enemy footwork, your own footwork, regularly. Usually good players are on here, emulate them a bit.
Even if you are a shielder sometimes you should try using a long spear, pike, American Bill, or some other support/long weapon and just follow good people around and watch how they play as you give them support/continuously polestun your teammates in the back by accident.
Realistically: Give up and go Cav or Ranged.
Also all the good players are spergs who have played this game for like a year, don't feel too bad.