First of all it should be said that you have to think of parrying as a normal part of your arsenal, this is no magic trick (dark bead *cough*).

A parry (regardless of the tool used) can be divided into 3 events:

• Start-Up Frames
  
• Parrying frames
  
• Recovery frames

Start-Up: During the start up time the character model prepares the parry.
Active frames: These are the only frames during the whole parry where the incoming hit will count as a parry
Recovery time: The time frame before you can do your next parry or any action in general.

So our goal is to get hit while we are in the active frames.
You may ask yourself when these different frames happen, this is what we will get into next

There's a huge variety of parrying tools not only in terms of looks but also function. Each parrying tool has different distributions of parrying frames.
There is not really a best parrying tool since it comes down to what the user prefers, generally light parrying tools are preferred such as the small shields or caestus due to them not only being light but also having longer active frames compared to let's say medium shields.

This is by now my shortest guide. But theres not a lot more to offer when it comes to parrying besides practice and the information I gave. There is advanced parrying techniques, aswell as some technical shenanigans but going into some of them needs a way more in-depth look and would go beyond the scope of this short guide. Nevertheless I hope this helped you out, if you have any requests regarding more content, I will make sure to add it once I have the time. Thank you very much for reading the guide.