The first thing to make sure you do is not get your first penal into a bad fight, wait for the 2nd one before you do anything silly.
The second thing you need to keep in mind is that the best distance to fight with penals against volks is 6 (a sandbag has length 5), do not get up to their face if you dont need to take cover from some other squad or to try to leave some red cover, since if just 2 squads are fighting the cover dont apply (minimum cover range of 10).
The third thing i would recommend is making the scout car, which need to be used to either hunt for the Kubel if they built one, otherwise try to force a retreat on their sturms, but beware of mines.
