If you're planning to 100% the single player campaign, do so before you try to reach the level cap (spoilers, not plot related)

As you may know, the campaign gives you access to a total of 9 weapons to play around with, and when you beat every stage with a particular weapon you get to use that weapon's replica in online mode (rip Hero Brella).

But what you may not yet know is that when you beat any given STAGE with every weapon, you get a meal ticket for Crusty Sean's food truck. These can be money tickets OR experience tickets.

With 27 stages and 5 bosses together in the game, you can get 32 meal tickets in total if you're crazy enough to beat every stage 9 times. So it might be smart to do this before you try to reach the level cap, as the many experience tickets will help you a lot.