Ok. first of all I'm new hear, but here me out.
Now number one. make sure all of your best weapons are upgraded all the way, and have mod's of your choice.( I prefer the Hot Steel/Highvoltage).
Second. make sure you have plenty of med-kits( large ones if possible) and any type of explosives.
third, bring a gun or a couple of knives for the suiciders.
(TIP) I like to gently go up to them and then when they start to grow quickly get away from them.
fourth. keep an eye out for Ammo, Med-Kits, energy drinks, anything. don't want to pass up anything use full.
number five. If you see a butcher and its running at you keep your distance and kick it then back away. let run at you again, kick it, then hit it, then repeat from step one.