The best trick is to prevent the problem from arising in the first place. To do this, make yourself a paper safe and always place the pack of photographic paper in it with the emulsion facing downwards. Now the only time you’ll be faced with the question is when you open a new pack. A paper safe saves you the hassle of fiddling with the original packaging; just lift the lid, take out the paper, turn it over and place it under the enlarger.
You can find out how to make one here:
http://www.fotolaborforum.eu/index.php?sho...ic=1077&hl=
Best regards, Wolfgang