Only by being consistent in your judging can you be fair to all those being judged.  To do this, you must keep your aesthetic guidelines in mind for every picture you review from start to finish.  This is easier said than done, especially in competitions with large numbers of entries.  As your senses are engaged with a seemingly endless succession of possibly very different photos, your criteria or their strictness of application may gradually drift, such that what got a 7 (out of 10) at the beginning is getting a 5 or a 9 at the end.

So don't let those ethereal clouds on that mountaintop in entry #38 distract you!  Thoroughly evaluate the picture for exposure, composition, etc., the same way you (hopefully) have judged all previous photos in the competition.