Here is my two cents. What has helped me is with sword pvp is:
1. LOWER YOUR SENSITIVITY! I see so many people trying to be an mlg 420 blaze it pvper with hyperspeed, but it helps so much when you turn down your sensitivity.
2. Do NOT jump on your first hit. You get less knockback when you don't jump, so you have a better chance of not getting combo'd and a better chance of comboing the other guy.
3. Block hit on the first hit in the fight. In the first hit, it is likely you and your opponent will both get hits, so what a good strategy to do it Block hit on the first hit, therefore you will get less knockback (again, better for combos), and you will deal less damage than the other guy.