Here is an example of a IFR flight plan from SIV to HUF direct to Practice Low Approaches (PLA).  The approach controller will see the PLA on his strip so it is worth placing in the remarks area.

Here is an example of a trip out of SIV for a VOR DME A back into SIV.  You cannot the route of flight blank, the computers at Flight Service will see it as a "non-flight".  You must put a fix in the route of flight even if you are returning to the same airport.  You could also use an intersection like "lisle" or "worke" in the route of flight.

Here is an example of a cross country flight plan.  Even though I only made it to Terre Haute, the process is the same.  You need an initial fix (lisle) then your route of flight listed as simply as possible.  Less is more in this case.

DVFR and DIFR

    These two flight plans are respective of whether you are filing VFR or IFR but you use them under the same circumstances.  You only need to file this type of flight plan if you are leaving the United States for Mexico or Canada or crossing the ADIZ (Air defense identification Zone) which is found over ocean areas outside the boundary waters of the United States (i.e. trip to the Caribbean).