Most people play Getting Over It without ever exploring the variety of ways players can interact with one another, esspecially in regards to PVP.
Sure, the Chimney Covenant, which lets you help other players in their world by engaging in Joyous Cooperation, is easily found, but others are more commonly overlooked on first playthroughs.

This guide is designed for those who want to Git Gud and experience the more mischievous side of Getting Over It player interaction.

The Way of Wrong is the first accessible PVP covenant.

Upon reaching Grill City simply head east on top of the first building's roof. There you will find the monument allowing you to join.

This covenant offers location-based invasions in and around Grill City during which you work together with regular enemies to defeat the world's host.
It is mostly only overlooked by players who do not take the time to explore and continue traveling west.

This covenant can be found by following the trail after the long jump instead of jumping onto the snowman. A pillar is located at the end of the trail which the player then has to jump over.

The Knights of the Booth are directly opposing the Serpent's Descendants covenant. After successfully invading as a Serpent's Descendant one's salt meter fills. Once the meter has reached a certain amount, Knights of the Booth start invading one until the salt is removed. A successful invasion as a Knight of the Booth grants one Broken Cauldron which can be turned in at the Telephone Booth in order to advance the covenant's ranks.

This covenant is probably the hardest to unlock, it requires one to defeat the optional Other-Side-Of-The-Tower Boss and then take a calculated plunge down the cliff.
I personally haven't been able to perform this, but that's only because only try-hards do it anyway.

This covenant lets other players summon one for one-on-one dueling, but only try-hards would want that anyways.

Lastly, the covenant for basic PVP invasions is accessed by following Ancient Snake Dimfollower Kaf down into the Abyss.
It is located close to the ending of the game and resets a lot of one's progress, therefore most player's tend to avoid this path.
I recommend not to join this covenant until one's second playthrough or later.

At rank 1 in this covenant the player obtains the Red Cauldron allowing for unlimited invasions.

Before anyone comments anything:
My uncle works at Nintendo, I think I know what I'm saying.