foreach $field (param) {
   # Isolate non-empty values
   my @values = grep { ! /^\s*$/ } param($field);
   next unless @values;  # Skip if nothing available

   # Establish a header line. Note that I added an "Other" class
   my $header = "Other:";
   $header = "First:" if $field =~ /Data_One/;
   $header = "Second:" if $field eq /Second_Part/;

   # Print it all. $, is the output record separator for prints
   local $, = "\n";
   print $header, @values, "\n";
}