In Persona 5 Strikers, you will need a lot of Persona Points to level up and upgrade your Personas, the main source of power for Joker. You can spend the points in the Velvet Room, increasing your Persona levels and learning new abilities.
When it comes to getting points, it is mostly done through play, but there are some things you can do to get them faster, keeping your power level ahead of the difficulty curve.
The easiest step to increasing your Persona Point income is to get the Bond Skill called Joker’s Wild. This will increase the number of masks that drop in the game, and you will gain more points each time you pick one up.
If you delete Personas in the Velvet Room, you will get some Persona Points in return. This means you need to decide if each Persona you pick up is useful for battles, fusion material, or as points.
The real source for Persona Points is simply grinding the Jails. This is less important in the early game, but in the late game as you start to reach the maximum level you will want to get as many high-level Personas as you can, so running the Jails over and over again can be a great way to do that. The 7th and 8th Jails should give you the best results, and the higher level Personas.