Shields selection according to the environment is key in preventing damage to the player. Shields can be used to block more than just physical damage. The Stone Parma shield has a blocking rating of 100 in physical damage. This is great for blocking an attack from The Body of Vengarl, however it only has a rating of 20 magic defense. To travel through the Shrine of Amana, you would want to select a shield such as Old Knights Shield with a magic blocking rating of 70. Less damage will be received by the player when blocking a magic spell with the Old Knights Shield than the Stone Parma (70 compared to 20). Pay attention to shield stats and their ability to block different types of enemy attacks to make the best use of shield selection (Darklurker has no physical damage attack, so you can select a shield with low physical damage reduction and high elemental protection)
Small Shields and Standard Shields can be used not only to block an enemy but to parry their attack as well. This allows a riposte, a free attack by the player for a high amount of damage. Enemy attacks can be interrupted with a parry (pressing the Strong Attack button for the shield) and requires practice to learn the timing. A good suggestion is to try and attempt to parry when the enemy weapon begins the attack animation. Tower Shields cannot parry.
Shields can also be used as a weapon. Use a small or standard shield two handed to enable it as an offensive weapon. The same can be done with tower shields two handed, however tower shields have their own attack animation. Press the heavy attack button with a tower shield to use it offensively.
Shields can still be used to block while attacking with some weapons such as spears. The player can hold the shield on guard while poking from behind it to minimize damage received during an exchange with an enemy also attacking the player.
Stamina management is important. If a player uses all of their stamina or gets hit and all their stamina is drained, they will be staggered and unable to move for a few seconds. This allows enemies to attack them at will. Pay attention to the green stamina bar and prepare to leave enough stamina for a strategic roll away from an enemy if needed. This also works the same for enemies. An enemy with a shield also can be staggered when they receive enough successful attacks on their shield.
The Guard Break is the counter to the shield. A player can use the guard break to stagger an opponent guarding behind their shield. This can be done to enemies in game and in player vs. player against another player online. If you use shields and are invaded by another player, be aware that they can use the Guard Break technique to break through your block and stagger your character, allowing them a free riposte for a high amount of damage.
You need to add information regarding the negatives of not meeting shield stat requisites. As far as I am aware these are: Higher stamina usage. Less stability. Reduced parry windows.