So to start, the F4 key. Never use it. There is no penalty for making your team wait every round, you will never be put into a lower priority.

Additionally, if you are vote kicked off be sure to press F4 before they succeed. This forces the timer to start and they will be unable to turn it off until someone joins and realizes to press F4 to unready. When matchmaking is taking forever this is a guaranteed defeat which may discourage a late joiner from staying. On top of this the late joiner will be unable to use the refund credit for no reason other than joining after the first wave has started.

Next, try to kill yourself during the upgrade selection. For whatever reason people dieing and respawning while one is upgrading causes MvM to eat the money and not give the upgrades. With money and upgrades being so important this can cripple the affected person.

Due to Valves sluggishness to address these longstanding issues, I felt it was necessary to make this guide.