I found the biggest challenge with Margit was that he telegraphs too much. Hell raise his weapon and then just hold it much longer than you think he will, you roll early and then he punishes you.
That move is interesting. If you hang back he does a spinning jump attack twice which is a little tricky to dodge but very consistent. You run towards him he will do a single strike. To me it felt like they were trying to teach you that this game needs you to disengage and sprint during fights. Either running away from him or running around to his backside work well for that.
On the converse is his upwards slash. That thing has basically no indicators and comes out faster than you're likely able to dodge... almost. If you fight him for a while it becomes apparent that when he wants to do this move he will walk towards you and otherwise will never do so. I couldn't tell if this was an intentional mechanic. Malenia later does something similar and it makes her fight much easier when you can understand her intentions before she begins doing any of her moves.
This is something that I learned much later on (50+ hours in), it's much easier to time with action than pause. By slot in a medium/light slash between enemy long winding/telegraphs, I can time the roll/parry much more consistent, and it's dying faster too.
Now that you mention it, I started doing this as well - without even really realizing it. Poking during the hold and then dodging immediately after is very effective.
On the converse is his upwards slash. That thing has basically no indicators and comes out faster than you're likely able to dodge... almost. If you fight him for a while it becomes apparent that when he wants to do this move he will walk towards you and otherwise will never do so. I couldn't tell if this was an intentional mechanic. Malenia later does something similar and it makes her fight much easier when you can understand her intentions before she begins doing any of her moves.