Like the title says, can someone please offer me a guide?
The highest level attainable in Borderlands 2 through XP gain is 72. Once you reach 72, head to Digistruct Peak and you can start gaining OP levels.Once you have done the first run at 72 (OP0), you need to save and quit your game, and when you go to reload your game you will be asked what OP level you want active, OP0 is just standard 72, you need to set it to OP1, and run the peak again to unlock OP2. Follow the same pattern until you have unlocked OP8, which is the maximum level.
One more thing sry does the amount of skill points you get change at all after 72?
No, you get a total of 68 skill points, effectively 67 because of the 1 you have to use for your action skill.
Just in case you get powerleveled (hopefully you don’t), you must have Ultimate Vault Hunter Mode unlocked as well.