My subs are always at the top. In my opinion, a sub should be in the file before the point where it's first used. If that isn't possible, for example when two subs call eachother, I put empty declarations above them. If you have subs before everything else, you don't have to wrap it in a BEGIN block if you need simple closures.

My sripts look like this:

#!/usr/bin/perl -w
use Module::Foo;
use Module::Bar;
use Module::Baz qw(foo bar);
use strict;

sub first {
    # ...
}

sub second {
    # ...
}

# main code, if applicable
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My modules look like:

package Module::Xyzzy
use Module::Foo;
use Module::Bar;
use Module::Baz qw(foo bar);
use base 'Exporter';
use Carp
use strict;

our @EXPORT_OK = qw(...);

sub CONSTANT () { 1 }

sub new {
    # I try to always put new before other methods
}

sub first {
    # ...
}

sub second {
    # ...
}

sub DESTROY {
    # If there's a DESTROY method, I put it at the end
}

# main code - that is: "1;" :)
__END__

=pod

That's right, I use __END__ and =cut, just to be sure. My documentatio
+n is NOT mixed
with the code. Whenever code is unclear, I comment it, but I dislike, 
+no I hate pod
and code mixed.

=cut
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It's just a matter of taste

++ vs lbh qrpbqrq guvf hfvat n ge va Crey :)
Nabgure bar vs lbh qvq fb jvgubhg ernqvat n znahny svefg.
-- vs lbh hfrq OFQ pnrfne ;)
    - Whreq