I think one of the most important concepts to take from programming is replacing abstract code with a function name that describe the work it is supposed to do. For example, I came across this code,

$fee = ($tfee / 100 + $sfee/100 + 0.0000001) * 100
$mfee = 200 if ($fee >= 100);

$fee = $mfee if $mfee;
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I don't even know what this does or why it is doing it. If they had done something like this, I would have a basic understanding of the what they are trying to accomplish.

$fee = determine_maximum_fee();

sub determine_maximum_fee {
  $fee = ($tfee / 100 + $sfee/100 + 0.0000001) * 100
  $mfee = 200 if ($fee >= 100);

  $fee = $mfee if $mfee;
  return $fee;
}
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To me, the difference between a good developer and a bad developer is being able to break code into functions that explain what the program is supposed to be doing. Something most beginning programmers do not understand.

Update: Changed sub determine_total_fee to sub determine_maximum_fee(), thanks to the Anonymous Monk for pointing out the error