"Best practice" is a matter of opinion (see various threads here regarding PBP). That said, I suppose Ref::Util is the best bet.

#!/usr/bin/env perl 
use strict;
use warnings;
use Ref::Util 'is_arrayref';

my $item = {
    x   => 'a',
    y   => ['b', 'c']
};

for my $key (keys %$item) {
    if (is_arrayref $item->{$key}) {
        print "Value for $key is an arrayref\n";
    } else {
        print "Value for $key is not an arrayref\n";
    }
}
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