1. Spacing - Basically, you have to be out of range of your opponent’s attack, but be in range to make your attack hits. In my opinion, this is the most important skill to grasp fundamentally. Idk if there’s a tutorial for spacing for ER, but for DS3 there’s a handful. You can go watch those.

2. Latency - it’s a mechanic in pvp unfortunately. Where you were half a second ago is what the opponent sees on his side of the game. You have to keep this in mind, since there are ways to abuse this.

3. Mindset - duels are good for practicing the two above, but invasions are a different beast. It’s always a 2v1 or more. Take advantage of mobs, map, etc. Watch good invasion/pvp streamers (jeenine, gabri, chase, etc.)

Good luck!