Have a close call and you lose even more points. To get your aircraft to land at an airport, you have to vector them according to the flow of traffic set presumably by surface wind direction. To land successfully, the aircraft on final must be at 1,000 feet and traveling in the right direction that's inline with the runway. To handoff VOR ships, they can approach the VOR station from any point of the compass but must be at an altitude of 10,000 feet. The 8,000 feet of airspace in between the prescribed altitudes are yours to do with as you please.
Assorted traffic comes in the form of arriving and departing aircraft.
Note that all aircraft will have 3 variable speeds in which you can decide upon, less the heavy aircraft that are only able to travel at one fixed and constant speed. Problem here is that it's not so simple when they want to transition thru the different 'airspaces' of the various airports within the Radar Screen's coverage. Perhaps you're trying the handoff the Cessna aircraft and you see an opening - you vector the aircraft to the station and set it's speed to high in hopes of beating that slower traffic. After all, the sooner they're out of your hair, the less problems you'll face. Then you see that you've already vectored another aircraft to that same station and set another transitioning thru the area.