While not specific to the '51, the below does apply. You should all read the latest issue of "the embedded muse". It can be found (and subscribed to) at ganssle.com.
The current issue is a bunch of excellent quotes about programming practices, the lack of which has led to questions in this forum.

a sample:

Or, as Brian Kernighan put it:
Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are, by
definition, not smart enough to debug it.

Erik