Sometimes it is good just to work out the steps of your program in different subroutines. It makes it very understandable and clear.
E.g. i am sleepy now, so

#!/usr/bin/perl
&stand_up();
&brush_teeth();
&go_to_bed();
&fall_asleep();
exit (0);

# i don't go into details about the subs now :-)
[download]

Sometimes it is very useful to store your reusable routines in separate files, in a common directory, and include them in your script, but be careful, too much include files messes up everything. Be smart. :-)

-- tune