use strict; # I can't emphasize that enough!
{
  package Common;
  use vars qw/ $Var1 @Var2 /;
  $Var1 = "some value";
  @Var2 = ( 1, 2, 3);

  if( $^V =~ m/^5\.6/ )
  {
    our $Var3 = "The 5.6 way to do the above";
  }
}

# Now in main:: name space
print $Common::Var1;
print reverse @Common::Var2;