How do I install Styrofoam ceiling tiles around lights, vents and fans?

Most of the time it works like this, before you start installing your tiles, lights, fans and vents get removed.  After you remove the lights and fans (make sure your power is off), cover the wires with proper covers and push them deep into the housing.  Once the wires are deep in the housing, you can install your tile over the wire housing and then just feel out the hole above it and use your razor knife to cut around it.  Vents are same, just make sure to turn your air conditioning or heating off so that you can install your tiles.