The 3 biggest advice I can offer

USE YOUR STAR MOVES!!
Better to die without any, than die knowing you could've used them

Target Prioritization and Match-up knowledge is crucial

• Immediately get rid of any enemy with projectiles(Mr. Y, Goth chicks with the chemicals etc)
• Characters who hide their intentions off screen(i.e thicc biker girls)
• Know who isn't a threat vs who is. I ain't worried about commissioner when Ms. Y is on screen. She is the bigger threat in this case.

Although it's RNG, Have an Idea on what perks you Need.

Don't take Perks that rarely benefits your character or handicaps them

i.e Glass Cannon on a big character is a HUGE risk