I think falling/shooting stars as random occurances, but you have the best chance of seeing one when its a clear night. It helps if you are somehwere where there is limited light pollution (Its really hard to see the stars when you are in a big city). Good luck!
While most meteors are more or less random, there are several meteor showers that occur regularly. http://funadvice.com/r/be8n32k2r2o
ooo i want to see a meteor shower!!