A lot of the offense in 4 on 4 is generated by the defenseman jumping into the rush. Think of your team as having two forwards, one "midfielder" and a defenseman.
The midfielder will switch between both positions in a sense... he'll act as both the offensive-minded defenseman, and the defensive minded forward. If you're going to forecheck aggressively, use this guy as the forward playing high. If you're forechecking conservatively, use this guy as a defenseman.
In your own end, play man to man if your team has wheels, and a zone defense if you don't. The more room there is, the harder it will be to play a zone defense.