When a hunter in SEWERS b4 they all go in pounce on the 4th person after 3 hav gone in.They can't get to u now.
in chapter 1 lv1 as a smoker go on the building where u can c da car with the alarm,hope u hav good team mates to slow them all down at this point so u can easily constrict the enemy, works for the smoker achievement.
when some one is being destroyed by Normy infecteds, attack them as any infected and if you die ur team and regs will destroy e'm, repeat this a lot to win.
as a survivor pick the shotguns and stay very far away from infecteds, only gun u need.
If u use any gun u want ( for ones where u hav a horde i recommend machine gun) you should win easy
for the use pistols only achievement, grab a 2nd one and use pain pills and use medy packs for easy win win win!!!