When I was playing the game on origin, I saw a lot of people quit because game is not fun anymore. So let's share some tips.
1. Do NOT waste your points on mystery boxes if you do not have juggernog.
2. Always start with generator 2 and go buy mp40.
3. Always check if there's any zombie before you revive somebody.
4. Never pick up the zombie blood that you get by powering generator 1.
5. Don't start the generator alone unless you have zombie shield and/or juggernog.
6. Jump on the mud areas.
7. Never try to buy perk or mystery boxes when zombies are gathering around you.