Use VOR radial and distance for points that aren't named fixes.
Use latitude and longitude for points that aren't named fixes.
Give the airport identifier or name for airports you are going to fly over, if they define the route.
When helpful, use plain language to describe the (highway, railroad, etc.) route.
In the US:
On the route portion of the flight plan, if you are flying direct to the first fix you don't say so (with "Direct," "DIR," "DCT," or D->) --you just begin listing the routing with that first fix. If you are going direct between fixes you don't say anything--you just list the fixes. If you are going from your last enroute fix direct to the airport you don't say anything--you just show that last enroute fix last. In those cases the route is direct. (A filed IFR flight plan route does not sound like the full route clearance; in the clearance the word "direct" is used for those direct segments).
US "Aeronautical Information Manual" 5-1: VFR flight plan, IFR flight plan, and direct flights.