I am well informed in how to parry, but I haven't mastered parrying with all weapons. I would like to find a area that spawns slow moving, slowly attacking monsters in low numbers (I would also appreciate you telling me the nearest bonfire).
Use the Cardinal Tower Bonfire as starting point. From there you have quick access to a lot of different Hollow mobs. These mobs have a variety of weapons, and attack with different speeds, and are great to practice parrying.
Additionally, they do not hit very hard. All in all, it is a area where you can easily control the settings and the pulls. If you blow out the wall, you'll have even more mobs to choose from very quickly.