Basic approach works best start by throwing a brick or bottle near hostile humans which brings infected running over once the chaos starts its usually smart to hang back since both groups will focus on each other for a bit when the infected start taking down enemies, survivors get disorganized making them easier targets

Keep an eye out for clickers and stalkers especially, since they move fast and hit hard maybe interesting you can line up shots while everyone is distracted and save ammo tip throwables are super useful here since infected have good hearing and will investigate any noise you make watch your timing though if youre too close theyll notice you instead of the other group

Feels similar to those mall fights from left behind where you could pit different groups against each other but now theres way more enemy types to work with like if you get shamblers involved things get really messy really fast since nobody wants to deal with that acid cloud